Which son did Ibrahim sacrifice: Ismaeel or Ishaaq?

The main reason for the contention are the passages in the Bible that mention explicitly that the son to be sacrificed was Ishaaq (as) not Ismaeel (as). This is actually a blatant interpolation whereby the name of "Ismael" was replaced with "Isaac" as shown by the groundbreaking research of Hamiduddin Farahi who spent ten years learning Hebrew specifically to research about this issue! The Bible mentions, for example: "Some time later God tested Abraham. He said to him, ‘Abraham!’ ‘Here I am,’ he replied. Then God said, ‘Take your son, your ONLY son, Isaac, whom you love, and go to the region of Moriah. ’ (Genesis 22) It follows that Abraham (as) was asked to sacrifice his only son which means that at that time he had no other son. The fact that this could only be Ismaeel (as) is evident from the following two passages of the Bible: Abraham was 86 years old when Hagar bore him Ismaeel. (Genesis, 16:16) Abraham was 100 years old when his son Isaac was born to him. (Genesis, 21:5) It is evident from these verses that Ismaeel (as) was fourteen years old at the birth of Isaac (as), and must have been offered for sacrifice before Isaac (as) was born because Abraham (as) had been asked to sacrifice his only son; after Isaac’s birth of course the words ‘your only son’ would be totally inappropriate and against reality. In the light of this evidence, it is obvious that the word Isaac mentioned in the passage above (indicated by italics) was inserted in place of Ismael.