What are the scholarly opinions about the difference between a prophet (nabi) and a messenger (rasool)?

Prophets and Messengers

Most scholars agree that “Every Messenger is a Prophet, but not every Prophet is a Messenger”, a prophet being one who receives revelation, and a messenger is one who receives revelation and is sent to a wayward nation to call them to Islam.

1. Al-Qurtubee said: "This is the correct stance, every Messenger is a Prophet, but every Prophet isn’t a Messenger" [Tafsir 12/45]

2. Al-Qadee Iyad said: "The correct opinion which the majority of the scholars hold is that every Messenger is a Prophet, but every Prophet isn’t a Messenger…" [ Al-Shifa]

3. Ibn Atteeyah said: "A Messenger is more specific than a Prophet. Most Prophets weren’t dispatched to nations. Every Messenger is a Prophet but every Prophet isn’t a Messenger" [Tafsir 10/ 307]

4. Al-Baghawee said: "Every Messenger is a Prophet, but every Prophet isn’t a Messenger." [Tafsir 4/126]

5. Al-Baaqa’ee said: "The correct thing to say is a Prophet is someone who is given divine revelation about an old or new legislation. And if he is sent to disbelieving people he’s a Messenger." [Nathm Ad-Durur fee Tanasab Ayat wa Sur 13/70]

6. Shawkani after mentioning the various definitions about the Prophet and Messenger said: "Based on all these meanings a Prophet is more general than a Messenger." [Nayl 1/30]

7. Al-Bayhaqee said: "Every Messenger is a Prophet, but every Prophet isn’t a Messenger." [Ashu’ib 1/383]

8. Ibn Taymiyyah said: "Every Messenger is a Prophet, but every Prophet isn’t a Messenger." [Majmu’ Fataawa 10/290]

Evidences

The following evidences are usually cited by scholars on this subject:

وَأَنزَلْنَا إِلَيْكَ الْكِتَابَ بِالْحَقِّ مُصَدِّقًا لِّمَا بَيْنَ يَدَيْهِ مِنَ الْكِتَابِ وَمُهَيْمِنًا عَلَيْهِ فَاحْكُم بَيْنَهُم بِمَا أَنزَلَ اللَّهُ وَلَا تَتَّبِعْ أَهْوَاءَهُمْ عَمَّا جَاءَكَ مِنَ الْحَقِّ لِكُلٍّ جَعَلْنَا مِنكُمْ شِرْعَةً وَمِنْهَاجًا وَلَوْ شَاءَ اللَّهُ لَجَعَلَكُمْ أُمَّةً وَاحِدَةً وَلَٰكِن لِّيَبْلُوَكُمْ فِي مَا آتَاكُمْ فَاسْتَبِقُوا الْخَيْرَاتِ إِلَى اللَّهِ مَرْجِعُكُمْ جَمِيعًا فَيُنَبِّئُكُم بِمَا كُنتُمْ فِيهِ تَخْتَلِفُونَ

"For each Messenger I sent a sharia and way of life" (Qur'an 5:48)

ثُمَّ اَرۡسَلۡنَا رُسُلَنَا تَتۡـرَا​ ؕ كُلَّ مَا جَآءَ اُمَّةً رَّسُوۡلُهَا كَذَّبُوۡهُ​ فَاَتۡبَـعۡنَا بَعۡـضَهُمۡ بَعۡـضًا وَّجَعَلۡنٰهُمۡ اَحَادِيۡثَ​ ۚ فَبُـعۡدًا لِّـقَوۡمٍ لَّا يُؤۡمِنُوۡنَ
Then We sent Our messengers in succession. Every time there came to a nation its messenger, they denied him, so We made them follow one another [to destruction], and We made them narrations. So away with a people who do not believe. (Qur'an 23:44)

اِنَّاۤ اَنۡزَلۡنَا التَّوۡرٰٮةَ فِيۡهَا هُدًى وَّنُوۡرٌ​ ۚ يَحۡكُمُ بِهَا النَّبِيُّوۡنَ الَّذِيۡنَ اَسۡلَمُوۡا لِلَّذِيۡنَ هَادُوۡا وَ الرَّبَّانِيُّوۡنَ وَالۡاَحۡبَارُ بِمَا اسۡتُحۡفِظُوۡا مِنۡ كِتٰبِ اللّٰهِ وَكَانُوۡا عَلَيۡهِ شُهَدَآءَ​​ۚ
Indeed, We revealed the Torah, containing guidance and light, by which the prophets, who submitted themselves to Allah, made judgments for Jews. So too did the rabbis and scholars judge according to Allah’s Book, with which they were entrusted and of which they were made keepers. (Qur'an 5:44)

وَلَـقَدۡ اَرۡسَلۡنَا مِنۡ قَبۡلِكَ فِىۡ شِيَعِ الۡاَوَّلِيۡنَ‏ وَمَا يَاۡتِيۡهِمۡ مِّنۡ رَّسُوۡلٍ اِلَّا كَانُوۡا بِهٖ يَسۡتَهۡزِءُوۡنَ‏
Certainly We did send Messengers before you among the nations which have gone by and whenever a Messenger came to them, they never failed to mock him. (Qur'an 15:10)

The Prophet (saw) distinguished between both groups:

عَنْ أَبِي ذَرٍ قَالَ : قُلْتُ : يَا رَسُولَ اللهِ، كَمْ الأْنِبَياء ؟ قال :مِائَةُ أَلْفٍ وَأَرْبَعَةٌ وَعِشْرُونَ أَلْفًا " قُلْتُ: يَا رَسُولَ اللَّهِ: كَمِ الرُّسُلُ مِنْهُمْ؟ قَالَ: " ثَلَاثُمِائَةٍ وَثَلَاثَةَ عَشَرَ جَمٌّ غَفِيرٌ
The Messenger (saw) was asked by Abu Dharr about the number of Anbiya and Rusul. He (saw) replied there were 124,000 Prophets among whom 315 were Messengers. (Musnad Ahmad, Tabarani and ibn Hibban)

In another narration the Prophet (saw) said the Prophet Adam (as) is a nabi:

أيُّ الأنبياءِ كان أوَّلَ؟ قال: آدمُ، قلتُ: يا رسولَ اللهِ، ونَبيٌّ كان؟ قال: نعمْ، نَبيٌّ مُكلَّمٌ
"Who was the first nabi? He (the Prophet) sad: Adam.
I said, O Messenger of Allah: 'Was he a prophet?'
He replied, 'Yes a nabi whom Allah spoke to.'" (al-Mustadrak 2966)

Some object to these narrations stating the narration is munkar - one of the chains has a weak narrator whilst the other chains omit the part stating "310 were messengers". But this hadith was narrated on the authority of Abu Dhar, Sadi ibn Ijlan, Jundub ibn Abdullah and Abdullah ibn Sakhr. There are some weak narrations of the hadith, but the meaning was narrated by several chains of narrators and in some authentic narrations as well, which elevates its rank.

On the other hand, there is a narration arguing Nuh (as) was the first rasool as in the narration of shafa'ah in the Day of Judgement:

ولكنِ ائتوا نوحًا، فإنه أولُ رسولٍ بعثه اللهُ إلى أهلِ الأرضِ
"Rather, go to Nuh as he is the first rasool sent to people of the earth." (Ibn Al-Arabi, Ahkam al-Qur'an, Vol. 4, p. 89)

So, there is a distinction between both terms. The same distinction was also made by Allah:

وَمَآ أَرْسَلْنَا مِن قَبْلِكَ مِن رَّسُولٍ وَلاَ نَبِيٍّ إِلاَّ إِذَا تَمَنَّىٰ أَلْقَى ٱلشَّيْطَانُ فِيۤ أُمْنِيَّتِهِ فَيَنسَخُ ٱللَّهُ مَا يُلْقِي ٱلشَّيْطَانُ ثُمَّ يُحْكِمُ ٱللَّهُ آيَاتِهِ وَٱللَّهُ عَلِيمٌ حَكِيمٌ

And We did not send before you any messenger or prophet except that when he spoke, Satan threw into it [some misunderstanding]. (Qur'an 22:52)

In another hadith when the Prophet (saw) was teaching al-Bara a du'aa before sleeping:

قَالَ فَرَدَّدْتُهُنَّ لأَسْتَذْكِرَهُنَّ فَقُلْتُ آمَنْتُ بِرَسُولِكَ الَّذِي أَرْسَلْتَ قَالَ ‏"‏ قُلْ آمَنْتُ بِنَبِيِّكَ الَّذِي أَرْسَلْتَ ‏"
"And as I repeated these words to commit them to memory, I said:" I affirm my faith in your Messenger (rasool) whom you sent."
He said: Say:" I affirm my faith in the Prophet (nabi) whom you sent." (Sahih al-Muslim 6544)

So, if both terms are the same the Prophet (saw) would have approved his du'a.

Juristic Analysis

Ultimately, the classical scholars held four different opinions on this question.

1. A prophet is the same as a messenger

The first set of scholars argued there was no difference. A prophet (nabi) was the same as a messenger (rasool) and the terms are interchangeable. An example of this is the contemporary scholar Zakyi Ibrahim who focuses on Qur'anic verses for his conclusion.

This opinion is open to critique because the Qur'an states:

وَمَآ أَرْسَلْنَا مِن قَبْلِكَ مِن رَّسُولٍ وَلاَ نَبِيٍّ إِلاَّ إِذَا تَمَنَّىٰ أَلْقَى ٱلشَّيْطَانُ فِيۤ أُمْنِيَّتِهِ فَيَنسَخُ ٱللَّهُ مَا يُلْقِي ٱلشَّيْطَانُ ثُمَّ يُحْكِمُ ٱللَّهُ آيَاتِهِ وَٱللَّهُ عَلِيمٌ حَكِيمٌ

And We did not send before you any messenger or prophet except that when he spoke, Satan threw into it [some misunderstanding]. (Qur'an 22:52)

If they had been same, then this verse is repeating the same term, breaking its usual eloquence and precision of wording.

Another argument holds a principle of Arabic grammar states when two similar things are cited together, separated by a waw, then one's attention is being drawn to the difference between the two (al-mughayarah).

Zakyi Ibrahim's response cites some examples which allegedly cite similar examples together such as “whoever is an enemy of Allah, His angels, His messengers, Gabriel and Michael, then verily, Allah is an enemy to the non-believers” (2:98).

Saying "Gabriel and Michael are angels, and their names are repeated after the angels have been mentioned. From this analysis, it must be concluded that repetition does not necessarily indicate difference." However his example does not hold up to scrutiny as the citation of angels, and then two angels in specific, is done for good reason - these two angels are criticised and Allah is addressing this criticism by highlighting them. They are therefore different as a category from other angels against whom there is no objection.


2. Messenger conveys revelation, whilst a Prophet does not

This widespread opinion states a prophet is inspired with revelation but is not expected to convey it, whilst a messenger is obliged to convey it to people.

This opinion is problematic as there is a hadith where the Prophet (saw) says:

عُرِضَتْ عَلَىَّ الأُمَمُ فَجَعَلَ يَمُرُّ النَّبِيُّ مَعَهُ الرَّجُلُ وَالنَّبِيُّ مَعَهُ الرَّجُلاَنِ، وَالنَّبِيُّ مَعَهُ الرَّهْطُ، وَالنَّبِيُّ لَيْسَ مَعَهُ أَحَدٌ
I saw all of the prophets (anbiya) on the day of judgement, and there was a prophet (nabi) with a big group, small group and no group. (Sahih al-Bukhari 5752)

This suggests prophets usually have some degree of followers having conveyed their revelation to others whilst some found no receptive audience.

It also does not make sense why someone would be inspired by Allah with a message but not expected to convey this message to others. No examples are cited of prophets in this category other than Ibn Hazm who cites Maryam (as) but scholars generally do not accept her as a prophetess.

3. Messengers bring a new Sharia

This opinion argues a messenger is someone who brings a new shariah (code of morals/ethics/laws), abrogating those preceding it, presumably because his qawm had abandoned the previous revelation and were lost. A prophet, however, follows the shariah of the previous messenger presumably because their qawm preserved it and live by it.

This view was supported by a large number of scholars including:

• Nasafi (Madarik at-Tanzeel, Vol. 3, p. 108);
• Baydawi (Anwar at-Tanzeel, Vol. 4, p. 133);
• Shawkani (Fath al-Qadeer, Vol. 3, p. 461);
• Qurtubi (al-Jami li ahkam al-Qur'an, Vol. 7, p. 298);
• Alusi (Ruh al-Ma'ani, Vol. 7, p. 157.)

However this faces immediate objections. In Sura Ghafir, Yusuf (as) is cited as a messenger (rasool) but he brought no sharia. Allah says:

وَلَقَدْ جَاءَكُمْ يُوسُفُ مِنْ قَبْلُ بِالْبَيِّنَاتِ فَمَا زِلْتُمْ فِي شَكٍّ مِمَّا جَاءَكُمْ بِهِ حَتَّى إِذَا هَلَكَ قُلْتُمْ لَنْ يَبْعَثَ اللَّهُ مِنْ بَعْدِهِ رَسُولًا كَذَلِكَ يُضِلُّ اللَّهُ مَنْ هُوَ مُسْرِفٌ مُرْتَابٌ
"And Yusuf had already come to you before with clear proofs, but you remained in doubt of that which he brought to you, until when he died, you said, 'Never will Allah send a messenger (rasool) after him.' Thus does Allah leave astray he who is a transgressor and sceptic." (Qur'an 40:34)

This verse is the clearest and key evidence in differentiating between both terms. Yusuf (as) was one of Bani Isra'il who followed the previous shari'ah. But what differentiated him from the other nabis of Banu Isra'il (such as Dawud, Sulaiman, Ishaaq and others) was that he was sent to a completely disbelieving nation. Similarly Bukhari cites Nuh (as) as the first messenger. Idrees (as) was a prophet coming before Nuh (as).

There are other subdivisions of this view: others argued the nabi is the one who receives the revelation while sleeping (or not receiving at all), but the rasool is the one who receives a revelation through Jibreel (as). As al-Baydawi says:

قِيلَ: الرَّسُولُ مَنْ جَمَعَ إِلَى الْمُعْجِزَةِ كِتَابًا مُنْزَلًا عَلَيْهِ، وَالنَّبِيُّ غَيْرَالرَّسُولِ، مَنْ لَا كِتَابٍ ، وَقِيلَ: الرَّسُولُ مَنْيَأْتِيهِ الْمَلَكُ بِالْوَحْي، وَالنَّبِيُّ: يُقَالُ لَهُ وَلِمَنْ يُوحَى إِلَيْهِ فِي الْمَنَامِ
"Some said: 'The messenger is one who combines the performance of miracles the revelation but the prophet is not as he received no book.
Others said: 'The rasool is the one to whom the angel brings the revelation, but the nabi is the one whom it is (in another way) said to him (maybe like a feeling or inspiration) and who receives revelation while sleeping.' " (Baydawi, Anwar at-Tanzeel, Vol. 4, p. 133)

But this is also improbable as prophet Adam (as) (and others) was a nabi and received revelation and spoke to Allah as per the hadith above. Prophet Dawud (as) received a book of duas (al-Zabur) and he was one of the nabis of bani Isra'il who followed the shari'ah of Musa (as).

4. Messengers convey revelation to a hostile nation

Ibn Taymiyyah advocates another opinion which seems to be the most persuasive of the four. He considers a linguistic perspective, asking what does the term nabi mean. Surah Naba (verse 2) uses the term to refer to news or information suggesting a nabi is one who informs others with the information he possesses. Rasool, however, means to send a delegate, envoy, emissary or ambassador, to a nation with whom one is usually not on good terms. From this reasoning, Allah sends messengers to nations who reject him (e.g., Nuh the first rasool, Lut, Hud, Salih, Yunus, Ibrahim, Musa, Yusuf, Isa and so on upto Muhammad), whilst a prophet is sent to people who already accept him due to their belief in the previous rasool (such as Idris, Yaqub, Ishaaq, Sulayman, Dawud and others).

The people of Adam (as) and Idris (as) did not worship others with Allah as they were created by Allah in a pure way. Later the Shayateen deceived them and made them worshipping others. (Sahih al-Muslim 6853) So the people of Nuh (as) were the first mushrikeen. As ibn Abbas said in interpreting the verse:

كَانَ النَّاسُ أُمَّةً وَاحِدَةً فَبَعَثَ اللَّهُ النَّبِيِّينَ مُبَشِّرِينَ وَمُنْذِرِينَ
"Mankind was one ummah; then Allah sent the prophets as bringers of good tidings and warners." (Qur'an 2:213)

He explained:

كَانَ بَيْنَآدَمَ وَنُوحٍعَشْرُ قُرُونٍكُلُّهُمْ عَلَىشَرِيعَةٍ مِنَ الْحَقِّ، فَاخْتَلَفُوا، فَبَعَثَ اللهُ النَبِيِينَ مُبَشِّرِينَ وَمُنْذِرِينَ
"There were ten centuries between Adam and Nuh. All people followed a shari'ah of truth. They disagreed, so Allah sent nabis, bringers of good tidings and warners." (Tabari, Jami al-Bayan, Vol. 4, p. 275, )

The same thing was narrated by Qatadah, Ikrimah and others, but Mujahid made it specific:

فَكَانَ أَوَّلَ مَنْ بَعَثَ نُوحًا
"The first who was sent was Nuh." (Ibn Kathir, Tafseer al-Qur'an al-Adheem, Vol. 1, p. 229)

As the narration above says Nuh (as) was the first rasool, so he was the first rasool when people deviated too much from the divine trajectory.
Yusuf (as) also was sent to people who were disbelievers, so he was called rasool.

Ibn Taymiyyah argued:

ٌفَالنَبِيُ هُوَ اّلذِي يُنَبِئُهُ اللهُ، وهُوَ يُنْبِىءُ بِمَا أَنْبَأَ اللهُ بِهِ؛ فَإِنْ أُرْسَِل َمعَ ذَلِكَ إِلَى مَنْ خَالَف أَمْرَ اللّهِ ليُبَلِغَهُ رِسَالَةً مِنَ اللهِ إِلَيهِ؛ فَهُوَ رَسُول
"The nabi is the one whom Allah informs and he informs people of what Allah has told him. But if he was sent with a message to those that go against Allah's commands, he is a rasool. But if he follows a shari'ah that came before him and is not sent to anyone to convey Allah's message to them, then he is a nabi and not a rasool." (Ibn Taymiyyah, al-Nubuwaat, Vol. 2, p. 714)

All the evidences support this view with no contradiction. As such it is the strongest position.

وَلَـقَدۡ اَرۡسَلۡنَا مِنۡ قَبۡلِكَ فِىۡ شِيَعِ الۡاَوَّلِيۡنَ‏ وَمَا يَاۡتِيۡهِمۡ مِّنۡ رَّسُوۡلٍ اِلَّا كَانُوۡا بِهٖ يَسۡتَهۡزِءُوۡنَ‏
(O Muhammad), certainly We did send Messengers before you among the nations which have gone by and whenever a Messenger came to them, they never failed to mock him. (Qur'an 15:10)

أَفَكُلَّمَا جَاءَكُمْ رَسُولٌ بِمَا لَا تَهْوَىٰ أَنْفُسُكُمُ اسْتَكْبَرْتُمْ فَفَرِيقًا كَذَّبْتُمْ وَفَرِيقًا تَقْتُلُونَ
But is it [not] that every time a messenger came to you, [O Children of Israel], with what your souls did not desire, you were arrogant? And a party [of messengers] you denied and another party you killed. (Qur'an 2:87)

فَإِنْ كَذَّبُوكَ فَقَدْ كُذِّبَ رُسُلٌ مِنْ قَبْلِكَ جَاءُوا بِالْبَيِّنَاتِ وَالزُّبُرِ وَالْكِتَابِ الْمُنِيرِ
Then if they deny you, [O Muhammad] - so were messengers denied before you, who brought clear proofs and written ordinances and the enlightening Scripture. (Qur'an 3:184)

لَقَدْ أَخَذْنَا مِيثَاقَ بَنِي إِسْرَائِيلَ وَأَرْسَلْنَا إِلَيْهِمْ رُسُلًا ۖ كُلَّمَا جَاءَهُمْ رَسُولٌ بِمَا لَا تَهْوَىٰ أَنْفُسُهُمْ فَرِيقًا كَذَّبُوا وَفَرِيقًا يَقْتُلُونَ
We had already taken the covenant of the Children of Israel and had sent to them messengers. Whenever there came to them a messenger with what their souls did not desire, a party [of messengers] they denied, and another party they killed. (Qur'an 5:70)

وَلَقَدْ كَذَّبَ أَصْحَابُ الْحِجْرِ الْمُرْسَلِينَ
And certainly did the companions of Thamud deny the messengers. (Qur'an 15:80)

ذَٰلِكَ جَزَاؤُهُمْ جَهَنَّمُ بِمَا كَفَرُوا وَاتَّخَذُوا آيَاتِي وَرُسُلِي هُزُوًا
That is their recompense - Hell - for what they denied and [because] they took My signs and My messengers in ridicule. (Qur'an 18:106)

وَلَقَدِ اسْتُهْزِئَ بِرُسُلٍ مِنْ قَبْلِكَ فَأَمْلَيْتُ لِلَّذِينَ كَفَرُوا ثُمَّ أَخَذْتُهُمْ ۖ فَكَيْفَ كَانَ عِقَابِ
And already were [other] messengers ridiculed before you, and I extended the time of those who disbelieved; then I seized them, and how [terrible] was My penalty. (Qur'an 13:32)

Other scholars like Razi argued in a similar vein:

"A nabi is one who is not given a new book, but rather establishes the book which was revealed to the rasool before him. He does not abrogate the book and the code of law which was in vogue before him. He sees the angel in a dream or the rasool of the time informs him that he has been chosen as a nabi." (Razi, Mafaatih al-Ghayb Vol. 23, p. 43)

Conclusion

Scholars differed in their views. Ibn Taymiyyah however explained this issue well. Prophets (anbiyaa) brought revelation to nations or peoples that were receptive or already accepting of revelation (e.g., Adam, Idris, Ismaeel, Ishaaq, Dawud, Suleiman or Yahya). Messengers (rusul) were sent to more hostile nations who had abandoned revelation (e.g., Nuh, Hud, Saleh, Lut, Yunus, Musa, Yusuf, Isa and Muhammad). Prophets are not messengers, but messengers can be prophets, where they develop followers who are receptive to their message.

References

Alusi, Ruh al-Ma'ani
Baydawi, Anwar at-Tanzeel
Ibn Al-Arabi, Ahkam al-Qur'an
Ibn Kathir, Tafseer al-Qur'an al-Adheem
Ibn Taymiyyah, al-Nubuwat
Nasafi, Madarik at-Tanzeel
Qurtubi, al-Jami li Ahkam al-Qur'an
Shawkani, Fath al-Qadeer
Razi, Mafatih al-Ghayb
Tabari, Jami al-Bayan
Zaky Ibrahim, A Prophet or a Messenger: How Bona Fide a Qur’anic Concept?

The Difference Between Nabi (نبي) and Rasul (رسول)

Some scholars claim that the Prophet PBUH became a nabi through the revelation of iqra, and he became a rasul through the revelation of Surah al-Muddaththir. This leads us to another tangent: what exactly is a nabi, what exactly is a rasul, and what is the difference between a nabi and a rasul, and what was our Prophet Muhammad PBUH?

There are many opinions, but for the sake of brevity, we will only mention four:

1. One group of scholars say there is no difference. Nabi = rasul; they are synonyms, just like tawba and istighfar are synonyms. This does not seem to be the strongest opinion, because of many reasons; of them is the verse in the Quran, "We didn't send before you either a rasul or a nabi except that..." [22:52]. Had nabi and rasul been the same thing, this would be against the eloquence of the Arabic language to phrase something like this. It doesn't make sense to put them together in this manner. So this is not the strongest opinion.

2. A nabi is one who is inspired by Allah with a revelation but he is not told to preach it to the people. Whereas a rasul is somebody who is told to proclaim it to mankind. This is problematic on multiple levels. Firstly, the ayah [22:52] above clearly says that nabi is also 'sent'. Also in Sahih Bukhari, the Prophet PBUH said, "I saw all of the prophets on the DoJ, and there was a nabi with a huge ummah, and there was a nabi and he had a small group, and there was a nabi and he had 5 people, and there was a nabi he had 2 people, and there was a nabi he had no people following him" - shows that nabis were also preaching to the people, and have followings. Also this opinion doesn't appear to be correct because even scholars are told if you conceal knowledge, you are going to be punished. In fact the Muslims are told, "بلغوا عني ولو آية" - so even the average Muslims has to preach. How then can somebody be inspired by Allah and he doesn't preach? Thus this opinion is also not the strongest.

3. A rasul is someone who has been given a new sharia (code of laws). Whereas a nabi is someone who follows the sharia of the rasul before him. This opinion seems to be good but it doesn't match up to all of the examples. E.g. By this definition, Yusuf AS wouldn't be a rasul. But the Qur'an [40:34] clearly mentions Yusuf as a rasul. Another example is: If a nabi is someone who follows the sharia of the previous prophets, Adam AS would have been a rasul. But in Sahih Bukhari, the Prophet PBUH said, "The first rasul is Nuh AS." So Adam is a nabi but not a rasul. Also Idris AS - he is not a rasul according to this same hadith. Yet another example: Dawud and Sulayman AS were rasul even though they followed the sharia of Musa AS. Dawud AS had Zabur - but Zabur contain nothing but praise, tasbih, and tahmid; with no law at all - shows that a rasul doesn't necessarily have to come with a new law. So all of these shows that the raw data doesn't match up with the hypothesis, so this third opinion is proven to be not true.

4. The correct opinion seems to be the one that Ibn Taymiyyah propounded. He says let's look at the linguistic meaning of nabi and rasul. Nabi comes from naba'a which means information. So a nabi is somebody who informs you what Allah wants him to inform - nabi has information from Allah and has to preach and teach - The word nabi automatically implies he is speaking to you a message from Allah. Rasul comes from arsala yursilu rasulan which means to send (a delegate/emissary/representative/ambassador). So a rasul is somebody Allah sends, generally to a nation that he is not on friendly terms with i.e. a nation that does not believe in him. Whereas a nabi teaches to a people that already accepts him. If you look at this definition, all the raw data fits into place. Did any of Adam's children reject him? No. Did any of Idris's people reject him? No. How about Nuh? People rejected him. And in Sahih Bukhari, the the Prophet PBUH confirms that he is a rasul. Yusuf AS is also a rasul because he is sent to the non-believers of Egypt. Dawud and Sulayman too had to fight to establish a kingdom, so they were rasul. Another classic example is Yahya AS and Isa AS; two cousins, their mothers were sisters. But one is a nabi and the other a rasul because they accepted Yahya and rejected Isa. So this definition seems to be precise.

And then Ibn Taymiyyah says:

Generally every rasul does have a new sharia (but this is not a rule, it's just a symptom/adjective which has exceptions).