After being rejected by the sons of Esau, God turned to the sons of Ammon and Moab and made the same offer: "Will you accept the Torah?" The Mekhilta DeRabbi Yishmael records their response with the same pattern of inquiry and refusal.
The sons of Ammon and Moab asked: "What is written in it?" God answered with the commandment: "You shall not commit adultery."
Their rejection was immediate and rooted in their own origin story. They pointed out that their entire nation was born from incest. Their ancestor Lot, nephew of Abraham, had fathered both Ammon and Moab through relations with his own daughters, as recorded in (Genesis 19:36): "And the two daughters of Lot conceived by their father." The very existence of these peoples was the result of the act the Torah would prohibit.
Their objection carried a brutal logic: "How, then, shall we accept it?" They were not merely saying they preferred to continue sinning. They were arguing that accepting a law against sexual immorality would retroactively delegitimize their own founding. To accept the Torah's prohibition would be to condemn the act that brought their nation into being.
Like the sons of Esau before them, the sons of Ammon and Moab were offered a genuine choice and declined it honestly. Each nation stumbled over the specific commandment that struck closest to home. God did not exempt any people from the offer. But each people, confronted with the Torah's demands, chose their own identity over the covenant.