When did Umar (ra) embrace Islam?

In a Nutshell: Scholars disagree on the exact year of Umar ibn al-Khattab's conversion. They suggest he converted between the fifth or ninth year of ba'thah (revelation). It is more probable, based on a closer reading of the evidences, that he converted in the sixth year of ba'thah (revelation). Context Scholars differ on the exact year of Umar ibn al-Khattab's (ra) conversion to Islam in Mecca. The eighth-century historian al-Amiri argued he converted in the fifth year of ba'thah: وَقِيلَ فِي الْخَامِسَةِ أَسْلَمَ عُمَرٌ "It was said Umar embraced Islam in the fifth-year" (Al-Amiri, Bahjat al-Mahafil, Vol. 1, p. 104) But ibn Abbas (ra) narrated he converted in the sixth year and ibn al-Jawzi and the ninth-century historian al-Hamiri narrated scholars' agreement on the fifth or sixth year. (Suhili, ar-Rawd al-Aneef, Vol. 3, p. 271, Al-Hamiri, Haqa'iq al-Anwar, p. 61, 178) Ibn Kathir however argued Umar (ra) embraced Islam as late as the ninth year of ba'thah: إِسْلَامُهُ قَبْلَ الْهِجْرَةِ بِنَحْوٍ مِنْ أَرْبَعِ سِنِينَ. وَذَلِكَ بعد الْبعْثَة بِنَحْوِ تسع سِنِين "His conversion was four years before the migration; i.e. nine years after ba'thah" (Ibn Kathir, as-Seera an-Nabawiyah, Vol. 2, p. 39) However, by reviewing details in the narrations of Umar's (ra) conversion, we could persuasively argue he converted in the sixth year of ba'thah. For example, Umar (ra) converted after the beginning of the migration to Abyssinia as ibn Hisham narrated: وَكَانَ إسْلَامُ عُمَرَ بَعْدَ خُرُوجِ مَنْ خَرَجَ مِنْ أَصْحَابِ رَسُولِ اللَّهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ إلَى الْحَبَشَةِ. "Umar embraced Islam after the migration of some of the companions of the Prophet (saw) to Abyssinia." (Ibn Hisham, as-Seera an-Nabayiyah, Vol. 1, p. 342) Before Umar (ra) became a Muslim, he had an interesting conversation with one of the migrants when this migration took place. Tabarani and ibn Ishaq narrated this conversation between Umar (ra) and the female companion Layla (ra) who said: كَانَ عُمَرُ بْنُ الْخَطَّابِ مِنْ أَشَدِّ النَّاسِ عَلَيْنَا فِي إِسْلَامِنَا، فَلَمَّا تَهَيَّأْنَا لِلْخُرُوجِ إِلَى أَرْضِ الْحَبَشَةِ، جَاءَنِي عُمَرُ بْنُ الْخَطَّابِ، وَأَنَا عَلَى بَعِيرِي أُرِيدُ أَنْ أَتَوَجَّهَ فَقَالَ: أَيْنَ يَا أُمَّ عَبْدِ اللهِ؟ فَقُلْتُ: آذَيْتُمُونَا فِي دِينِنَا، فَنَذْهَبُ فِي أَرْضِ اللهِ، حَيْثُ لَا نُؤْذَى، قَالَ: صَحِبَكُمُ اللهُ، ثُمَّ ذَهَبَ، فَجَاءَنِي زَوْجِي عَامِرُ بْنُ رَبِيعَةَ، فَأَخْبَرْتُهُ بِمَا رَأَيْتُهُ مِنْ رِقَّةِ عُمَرَ، فَقَالَ: تُرَجِّينَ أَنْ يُسْلِمَ؟ فَقَالَ: وَاللهِ لَا يُسْلِمُ حَتَّى يُسْلِمَ حِمَارُ الْخَطَّابِ "Umar was one of the toughest people against us in our (early days of) Islam. When we prepared to migrate to Abyssinia, Umar came when I was riding my camel ready to leave. He said, 'Where are going, O Umm Abdullah?' I replied, 'You harmed us in our deen and we are going to (settle) in the land of Allah (i.e. anywhere on earth) where we may face no harm.' He said, 'May Allah help you,' then he left. When my husband Amir ibn Rabi'ah came, I told him what I saw of the softness of the heart of Umar. He ridiculed, 'Do you wish him to be a Muslim! By Allah, his donkey would become a Muslim before him.'" (Ibn Ishaq, as-Siyar wa al-Maghazi, p. 181, Tabarani, al-Mu'jam al-Kabir, Vol. 25, p. 29, Ibn al-Athir, Asad al-Ghabah, Vol. 7, p. 249, Ibn Hajar, al-Isabah fi Tameez as-Sahabah, Vol. 8, p. 102) Therefore, the possibility of the fifth year is unlikely to apply here as they migrated in the fifth year of ba'thah. (Al-Hamiri (d. 900 A.H.), Haqa'iq al-Anhar, p. 61, 178) What could precisely identify the year of his conversion is the age of his son Abdullah. Ibn Umar (ra) narrated: لَمَّا أَسْلَمَ عُمَرُ اجْتَمَعَ النَّاسُ عِنْدَ دَارِهِ وَقَالُوا صَبَا عُمَرُ‏.‏ وَأَنَا غُلاَمٌ فَوْقَ ظَهْرِ بَيْتِي "When Umar embraced Islam, all the (disbelieving) people gathered around his home and said, "Umar has embraced Islam." At that time, I was still a boy (ghulam) and was on the roof of my house." (Sahih al-Bukhari 3865) Ibn Hajar notes Abdullah ibn Umar narrated he was about five years old when his father converted. We know he was 14 years old at the battle of Uhud (16th year of ba'thah). So, ibn Umar (ra) was born in the second year of ba'thah + 5 years of his age at conversion = 7 for Umar's conversion. Ibn Hajar stated: قَوْلُهُ وَأَنَا غُلَامٌ فِي رِوَايَة أُخْرَى انه كَانَ بن خَمْسِ سِنِينَ وَإِذَا كَانَ كَذَلِكَ خَرَجَ مِنْهُ أَنَّ إِسْلَامَ عُمَرَ كَانَ بَعْدَ الْمَبْعَثِ بِسِتِّ سِنِين أَو بِسبع لَان بن عُمَرَ ... كَانَ يَوْمَ أحد بن أَرْبَعَ عَشْرَةَ سَنَةً وَذَلِكَ بَعْدَ الْمَبْعَثِ بِسِتَّ عَشْرَةَ سَنَةً "Ibn Umar's statement 'I was ghulam' in another narration he was 'five years old.' If so, we would deduce that the conversion of Umar (ra) took place 6 or 7 years after ba'thah because ibn Umar ... was 14 years old in the day of Uhud and it was 16 years after ba'thah." (Ibn Hajar, Fath al-Bari, Vol. 7, p. 178) Given the Arabs used to count the year seven, for example, at its beginning, as well as the other narrations of the companions of his conversion at the sixth year, it is probable Umar (ra) converted around the sixth year of ba'thah. Conclusion Scholars disagree on the exact year of his conversion. They suggest he converted between the fifth or the ninth year of ba'thah (revelation). Reviewing the evidences, it is probable that he converted in the sixth year of ba'thah. References Al-Amiri, Bahjat al-Mahafil; Al-Hamiri, Haqa'iq al-Anwar; Suhili, ar-Rawd al-Aneef; Ibn Kathir, as-Seera an-Nabawiyah; Ibn Hisham, as-Seera an-Nabayiyah; Ibn Ishaq, as-Siyar wa al-Maghazi; Tabarani, al-Mu'jam al-Kabir; Ibn al-Athir, Asad al-Ghabah; Ibn Hajar, al-Isabah fi Tameez as-Sahabah; Ibn Hajar, Fath al-Bari.