Sforno on Genesis 22:23/ספורנו על בראשית כ״ב:כ״ג

1ובתואל ילד את רבקה, the person relating all this to Avraham added that Betuel, a son of Nachor’s proper wife, sired Rivkah. The meaning of the message was that there had been born in his own family a girl who would be a suitable wife for Avraham’s son so that he would not have to look for such a wife among the Canaanites surrounding him.