“Abraham Begot Isaac”

And these are the generations of Isaac, Abraham’s son: Abraham begot Isaac. (Genesis 25:19)

וְאֵלֶּה תּוֹלְדֹת יִצְחָק בֶּן אַבְרָהָם – אַבְרָהָם הוֹלִיד אֶת יִצְחָק. (בראשית כ"ה, יט)

Usually, when the Torah describes someone’s generations, it lists descendants and events affecting him and his family. Yet in Isaac’s generations, although he is Abraham’s son, it returns to the past and emphasizes the obvious: “Abraham begot Isaac.” Why?

The verse seems intended to emphasize Isaac’s distinctive standing as Abraham’s natural heir, unlike Ishmael. Though firstborn, Ishmael was born to Hagar the Egyptian, Sarah’s handmaid, and therefore was unsuited to continue Abraham’s path. As the LORD told Abraham: “for in Isaac shall seed be called to thee” (Genesis 21:12).

Thus, when introducing Ishmael’s generations a few verses earlier, the Torah emphasizes his mother’s nationality and low status:

Now these are the generations of Ishmael, Abraham’s son, whom Hagar the Egyptian, Sarah’s handmaid, bore unto Abraham. (Genesis 25:12)

וְאֵלֶּה תֹּלְדֹת יִשְׁמָעֵאל בֶּן אַבְרָהָם, אֲשֶׁר יָלְדָה הָגָר הַמִּצְרִית שִׁפְחַת שָׂרָה לְאַבְרָהָם. (בראשית כ"ה, יב)

It distances Ishmael from Abraham by identifying him as the son of Hagar, an Egyptian and Sarah’s handmaid, who did indeed bear him to Abraham. By contrast, introducing Isaac’s generations, it emphasizes his natural continuation of Abraham’s path and states directly: “Abraham begot Isaac.”