Rashi on Deuteronomy 23:9/רש"י על דברים כ״ג:ט׳

1בנים אשר יולדו להם דור שלישי וגומר THE CHILDREN THAT ARE BORN UNTO THEM [MAY COME INTO THE ASSEMBLY] IN THEIR THIRD GENERATION — other nations, however, since they did not sin against you may be admitted at once if they acknowledge the tenets of Judaim. — Thus you learn that he who causes a man to sin does him greater harm than if he kills him, for he who kills him, kills him only as regards this world, while he who causes him to sin puts him out of this world and the world to come. Therefore Edom, though he met them with the sword was not to be abhorred utterly, and similarly the Egyptians who drowned them (their male children), while those (the Ammonites and Moabites) who caused them to sin were to be utterly abhorred (Sifrei Devarim 252:3).