Descendants awarded for an ancestor’s deed
Many Jews accept as true the somewhat mystical notion that the rewards for a person’s good deeds, if they are not collected during the individual’s lifetime, are stored somewhere, like a bank account, and can be drawn upon later to help the descendants of the individual who performed the unrewarded good deeds. This idea is called in Hebrew zechut avot, “merits of the fathers.” Some Jews go so far as to say that not only descendants can cash in the rewards, but even people unrelated to the original actors. Still others feel certain that Jews today are aided by the zechut avot of past Jewish figures such as Abraham, Isaac, Jacob, and even Moses, Joshua, Daniel, and others. Some feel that the world is sustained by the zechut of current “saintly men,” thirty-six of them.
A large number of rabbis believed and still believe in the concept. It is found in the Talmud and Torah commentaries. But the notion is not accepted by all rabbis. The Palestinian Aramaic translations of the Bible, Pseudo-Jonathan and Neophyte, for example, mention the idea, but it is not in the rational rabbinically endorsed Aramaic translation Targum Onkelos.
Belief in the notion is reinforced by the opposite idea developed in the fourth century, but not before that date, called “original sin,” that people today are punished because of the misdeed of Adam and Eve who ate the fruit of the “Tree of Good and Evil” in Genesis 3. Both ideas are contrary to the view of the Torah that lays responsibility for deeds on the perpetrator.
A commentary on Samuel 30 is a good example of how some rabbis thought that zechut avot was implemented. It is bizarre. When David and his band of six hundred soldiers were absent from their encampment at Ziklag, when David left women and children in the insufficiently guarded camp, a marauding horde of Amalekites seeking spoils attacked the camp, burnt it, and seized women and children as captives, as well as a wealth of cattle and other loot. When David and his troop returned and discovered the disaster, they pursued the Amalekites and killed every one of them “except for four hundred young men who rode on camels and fled.”
Midrash Genesis Rabba 78:15 wonders why were the four hundred able to escape? The obvious answer is in the verse itself. They were seated on camels, fled the speedily, and David’s men were unable to catch them. But this answer failed to satisfy these rabbis who resorted to zechut avot.
The four hundred Amalekites were saved as a reward for the deed of the band of four hundred men who accompanied Esau when he met his brother Jacob. While Jacob feared that Esau and his band would harm him and his family as retaliation for Jacob taking their father’s blessing that their father meant for Esau, they did not do so. After some conversations between the brothers, Genesis 33:1 states “Esau left.”
While only Esau is mentioned in 33:1, it is obvious that it means Esau and his company. But the rabbis did not see it this way. They took the words literally and felt that, although the Bible does not say so or even otherwise hint at it, Esau left alone. While the brothers were talking, Esau’s companions left, unwilling to participate, unwilling to harm Jacob and his family.
Genesis Rabba remarkably adds that the four hundred Amalekites were saved during David’s attack because of zechut avot, the good deed of Esau’s band of four hundred. In short, the arch enemies of Israel, Amalekites, a nation the Torah states should be utterly destroyed, were saved because Edomites, not their ancestors, but members of another tribe, had compassion centuries earlier upon Jacob’s family.
 A lot of Jews accepted this bit of Christian theology. It is reflected in the Yom Kippur Mincha prayer: “Do not hold against us the sins of those who came before us.” The Koren Yom Kippur Mahzor, Koren Publishers, 1962, 2012, page 1058.
 Jewish prayer books are a compendium of diverse poems and prayers, from rationalists and mystics, old and new ideas, designed to prompt thought, including many ideas that are contrary to the beliefs of many Jews. The Musaf service for Shabbat which prays for a restoration of sacrifices is a good example, as is the mystic poem Anim Zemirot that describes God wearing tefillin.
 Exodus 17:16 and Deuteronomy 25:19.