The good deeds of the ancestors contribute to the welfare of their descendants. The expression, "You remember the good deeds of the patriarchs," is repeated three times daily in the opening benediction of the Shemoneh Esrei prayer.

The zechut avot concept, in Jewish theology, is expressive of the idea that individuals profit in the their lifetime by the meritorious acts of their ancestors. The Torah, in the second of the Ten Commandments, clearly indicates that the benefits of a man’s good deeds will extend indefinitely, implying that God’s mercy in rewarding righteousness infinitely transcends his anger in punishing the sinful (Shemot 20:6; Devarim 7:9).

Zechut Avot has also been interpreted to imply that a person is best able to advance on the road to moral perfection if he starts with the accumulated spiritual heritage of righteous ancestors. The earliest use of the phrase zechut avot is in the Ethics of the Fathers, where we read: "Let all who work for the community do so from a spiritual motive, for then the merit of their fathers will sustain them, and their righteousness will endure forever" (Avot 2:2)

What then is Zechut Avot? The Ramban describes that "the deeds of our fathers are a signpost for the children." And that this is a cardinal rule of Jewish history. In his commentary on Parshat Lech Lecha he writes; " I will tell you a rule to be applied throughout the parshiot of Avraham Yitzchak and Yaakov. The Rabbis stated this rule as “everything that happened to the fathers is a sign for the children”. The Torah tells stories, at length, about journeying or well digging …one might think that these are meaningless detail but in reality they reflect something of the future. When an event occurs to one of the prophets who are our forefathers, he will understand that a form of these occurrences will occur as well to his descendants.”