“And these are the generations of Isaac, Abraham’s son. Abraham fathered Isaac.”
My rabbis have taught me that repetition in the Bible is not repetition. Each time a similar phrase or a redundancy appears in the text, it is neither a repetition nor a redundancy. Instead, each is a separate and unique teaching moment. This belief stems from the idea that is there is redundancy in the text, then a portion of the Biblical text can forever be removed and we would be none the lesser for it. The Rabbis would say, “Heaven forbid!” In the prophets, it states, “…my word… that goes out of my mouth; it shall not return to me void, but it shall accomplish that which I please, and it shall prosper in the thing for which I sent it.” Therefore, the repetitious passages are there for the sake of exegesis. Take our passage for today: “Isaac, Abraham’s son. Abraham fathered Isaac.” On the surface, there’s a redundancy, but I would like the opportunity to show that there is indeed two separate important points being made here.
Before the birth of Isaac, Abraham had an encounter with the king of Gerar named Avimelech. In the initial encounter, the Biblical text does not provide enough information to determine the events of the encounter, but Rashi has a perfectly good explanation. Rashi argues that when a stranger arrives, it is proper to inquire of his needs and well being [to determine if the guest requires shelter, drink, or food] – not whether his female companion is a married woman. Since Avimelech and his minions inquired immediately as to the maritability of Sarah, Abraham automatically believed there was no fear of God in this place.
Once Hashem intervened and caused Avimelech to return Sarah, the Torah states that Hashem “remembered Sarah… and Sarah conceived.”
Returning to our passage, the text says, “And these are the generations of Isaac, Abraham’s son. Abraham – not Avimelech – fathered Isaac.”
Speaking of the king of Gerar, we see him in Genesis 20 and 21 interacting with Abraham, but we also see Avimelech in Genesis 26 encountering Isaac. We automatically assume it’s the same guy, but is it? A total of 76 years pass between Genesis 20 and 26. Considering that Abraham lives to see 175 years, it’s possible. However, when we take to account that King David dealt with Avimelech, it’s more likely to be a title than an actual person’s name. However, in the case of Gideon’s son, it is a name.
 i.e., Torah Portion
 Genesis 25:19 – 28:9
 Isaiah 55:11
 Genesis 20:1-18
 Genesis 20:11
 Genesis 21:1-2
 One year passes between the abduction and the birth of Isaac, Isaac lived 40 years before marrying Rivkah, Isaac and Rivkah wait 20 before the birth of the twins, and the twins are 16 years of age when one sells the birthright to the other at the funeral of Abraham. Isaac’s encounter with Avimelech occurs shortly after the funeral of Abraham.
 Psalms 34:1; reference 1 Samuel 21:11-16 as well
 Judges 8:30-9:56, 2 Samuel 11:21