Bereishis 25:21 – And Isaac prayed to the Lord opposite his wife because she was barren, and the Lord accepted his prayer, and Rebecca his wife conceived.
Gemora Yevamos 64a: It should have said that the Lord accepted “their” prayer. Why does it say that the Lord accepted “his” prayer? To teach that the prayer of a “righteous person” who is the child of a “righteous person” is more listened to than the prayer of a “righteous person” who is the child of an “evil person”.
Torah Temimah Colloquial Translation on Note #14
See what is written in the Shulchan Aruch, Orach Hayim Section 53 and also in the Taz sub-section 3 in the name of the Bach; and in the Maharshal who deduced from this teaching that it is better to look for a prayer leader who is the son of a righteous person. Note that the Taz disagrees with this because of the general principle that “God desires the heart.” It is amazing that the Taz does not reply at all to the above teaching from the Gemora that [indeed] the prayer of a righteous person, the son of a righteous person is preferable.
Rather, it seems to me, that a person who has better personal qualities is more preferable even if he may be the son of an evil person. Therefore, it is better to give such a person preference [in choosing a prayer leader] over a “righteous person the son of a righteous person” who doesn’t have as many good personal qualities.
It appears that a proof to this opinion can be brought from the Gemora Taanis 25b where it relates a story about Rabbi Eliezer who led the congregation is prayers, but nevertheless rain did not fall. Rabbi Akiva then led the prayers and subsequently it rained. The [other] rabbis were murmuring concerning the slight that had occurred to the honor of Rabbi Eliezer since his prayers were not answered. Suddenly a voice rang out from heaven and stated: “It was not because this person (Rabbi Akiva) is greater than this person (Rabbi Eliezer) but rather it is due to the fact that Rabbi Akiva has conquered his natural tendencies while Rabbi Eliezer has not needed to conquer his natural tendencies.”
Behold, it is well known that Rabbi Akiva is the son of converts. Thus, in relation to him, Rabbi Eliezer is a “righteous person, the son of righteous people”. Nevertheless, it was Rabbi Akiva’s prayer that was answered because of the personal characteristic that he had which Rabbi Eliezer did not have.
Editor’s Note: I think many people instinctively respond the same way as the Torah Temimah to the idea that “the prayer of a righteous person the child of a righteous person is more listened to than the prayer of a righteous person the child of an evil person”. Our instinctive response is that “God desires the heart” and it should not matter who a person’s parents were. The Torah Temimah then goes on to prove that this is a view supported by our tradition by citing the Gemora Taanis 25b.