“The elder gave birth to a son, and called his name Moav; he is the ancestor of the Moavites to this day” (Genesis 19:37). “The younger too gave birth to a son, and called his name Ben-Ami, he is the ancestor of Benei Amon to this day” (Genesis 19:38). “The elder gave birth to a son…” – Rabbi Yudan in the name of Rabbi Aivu: The elder daughter, because she demeaned her father’s honor and called his [her son’s] name Moav, meaning from father,35By calling her son Moav she made the act of incest public, which demeaned her father’s honor. the verse said: “Do not besiege Moav, and do not provoke war with them” (Deuteronomy 2:9) – you may not wage war with them, but you may breach their riverbeds, or burn their stacks of grain with fire.36You may intimidate them in other ways, as long as you do not wage war against them.
But the younger daughter, because she spared her father’s honor and said: “And she called his name Ben-Ami” – meaning the son of the one who was together with me, the verse states: “Do not besiege them and do not provoke them” (Deuteronomy 2:19) – at all. Rabbi Yehuda ben Rabbi Simon and Rabbi Ḥanin said in the name of Rabbi Yoḥanan: Lot’s daughters were going to violate a transgression,37This opinion maintains that Lot’s daughters acted immorally. yet they were remembered favorably [by God].38God granted them pregnancies and great nations emerged from them.
By what merit? It was due to the merit of Moav – the one who [mi] is the father [av], as it is stated in Abraham’s regard: “For I have made you the father of a multitude of nations” (Genesis 17:5).