TT #4 · Parashas Toldos · Passuk 25:21
Yitzchak pleaded with Hashem on behalf of his wife, because she was infertile; and Hashem responded to his plea, and his wife Rivkah conceived.
Torah Temimah points to Yevamos 64a. E-Daf · Sefaria — Yevamos 64a
“And He responded to him” — it should have said “to them.” Rather, the prayer of a righteous person who is the child of a righteous person is not comparable to the prayer of a righteous person who is the child of a wicked person.
Custom (Bavli — prayer of tzaddik ben tzaddik vs. tzaddik ben rasha)
The prayer of a righteous person who is himself the child of a righteous person is more effective than that of a righteous person whose parent was wicked.