No Generation Gap

And these (v’eileh) are the generations of Isaac, Abraham’s son: Abraham fathered Isaac.

                                                             Genesis 25:19

Midrashim as well as many classical commentators note the apparent redundancy of our verse, offering various explanations.

My father suggested that the addition of the phrase “Abraham fathered Isaac” is intended to stress that there was no generation gap between Abraham and Isaac. Abraham was Isaac’s spiritual, as well as physical father. The relationship between father and son was a deeply spiritual one, with Isaac following in Abraham’s footsteps, and devoting his life to the same ideas and ideals which had guided Abraham’s life: a quest to achieve Godliness in this world through Torah.

In contrast, concerning Ishmael, the verse [25:12] states “Now these are the generations of Ishmael, Abraham’s son, whom Hagar the Egyptian, Sarah’s handmaid bore unto Abraham,” since Ishmael did not follow in his father’s ways.

Our Sages tell us that Abraham minted a coin. On the obverse the coin had the image of an elderly couple and the reverse side had the image of a young couple. My father explained that the Sages teach that Abraham’s coin expressed the ideal of unity and continuity of generations.

My father’s comments are implied in two Midrashim quoted in Torah Shleima on our verse:

There are sons who dishonor their fathers and fathers who dishonor their sons. This was not the case with Abraham and Isaac.

                             Midrash Tanḥuma Yashan Toledot: 1

and

The verse teaches us that Abraham and Isaac were equal to each other.             Mishnat Rebbi Eliezer 5:92

Indeed, that “Abraham fathered Isaac” is the reason that Isaac was a willing participant in the akeida. Abraham trained his son in self-sacrifice.