Abraham prayed to God, and God healed Abimelech and his wife and his maids, so that they bore children. For the LORD had closed fast all the wombs of the household of Abimelech because of Sarah, Abraham's wife. (Genesis 20:17–18)

Abraham was 100 years old. For all of his married life he had hoped for and prayed for the birth of a son, but Sarah, his wife, was barren. Her womb was closed. Ironically, when Abraham’s enemy Abimelech abducted Abraham’s wife Sarah, God sealed the wombs of all Abimelech’s wives. Even those women who were about to give birth found that they could not bear their children. The Talmud says, “It was stated at the academy of Rabbi Yannai that even the hens belonging to Abimelech could not lay their eggs.” (b.Bava Kama 92a quoting Genesis 20:18)

After Abimelech returns Sarah to Abraham, he asks Abraham to pray for him. Abraham prays for the healing of Abimelech’s household. Rabbinic literature uses this episode from Abraham’s life as a model of forgiveness:

From where do we learn that an injured person who refuses to forgive his injurer (when he apologizes) is called a cruel person? From the words, “Abraham prayed to God, and God healed Abimelech…” (b.Bava Kama 92a Genesis 20:17)

Whoever is merciful to his fellow is certainly a son of our father Abraham, and whosoever is not merciful to his fellow is certainly not a son of our father Abraham. (b.Beitzah 32b)

The irony is that Abraham’s prayer avails children for Abimelech and his wives immediately. Furthermore, it is immediately after the Torah tells us that Abraham prayed for Abimelech’s wives—that their wombs would be opened—that we read, “Then the LORD took note of Sarah as He had said, and the LORD did for Sarah as He had promised. So Sarah conceived and bore a son to Abraham in his old age…” (Genesis 21:1).

Not until Abraham prayed for others was his prayer for himself and his wife answered. The medieval commentator Rashi says that the Torah put the passage regarding Abimelech’s wives just before the conception of and birth of Isaac intentionally. It is to teach us that whoever seeks mercy for another by praying for his need when he himself is needful of the same will have his own need met. At the very least, we learn here the principal of praying for others before ourselves.