“The sons of Abraham were Isaac and Ishmael.”
The final separation will come with the lineage of Isaac to Israel and the separation from Ishmael the first born. The importance of Abraham cannot be overemphasized as his name appears over 2,500 times in the biblical literature. The story of Abraham is covered in Genesis, chapters 12-25 that goes into great detail about his life and travels. The birth of (1) Ishmael is found in Genesis, chapter 16. His mother was Hagar, the Egyptian slave girl of Sarai. Abraham had sex with her at the request of Sarai, who wanted Abraham to have a child. This later created friction between Hagar and Sarai. The birth of (2) Isaac can be found in Genesis, chapter 21, based on the Yahweh promise in chapter 17. In somewhat of a miraculous event, Sarai bore a child at the age of 90. Once again, after the birth of Isaac there was friction between Sarai with her son Isaac and Hagar with her son Ishmael, so Sarai dismissed Hagar with her son Ishmael. Abraham was willing to sacrifice Isaac if it was the will of God.