God bade Moses impress upon the Jews to repulse no heathen should he desire conversion, but never to accept an Amalekite as a proselyte. It was in consideration of this word of God that David slew the Amalekite, who announced to him the death of Saul and Jonathan; for he saw in him only a heathen, although he appeared in the guise of a Jew.
Part of the blame for the destruction of Amalek falls upon his father, Eliphaz. He used to say to Amalek: "My son, dost thou indeed know who will posses this world and the future world?" Amalek paid no attention to his allusion to the future fortune of Israel, and his father urged it no more strongly upon him, although it would have been his duty to instruct his son clearly and fully. He should have said to him: "My son, Israel will posses this world as well as the future world; dig wells then for their use and build road for them, so that thou mayest be judged worthy to share in the future world." But as Amalek had not been sufficiently instructed by his father, in his wantonness he undertook to destroy the whole world. God, who tries the reins and the heart, said to him: "O thou fool, I created thee after all the seventy nations, but for thy sins thou shalt be the first to descend into hell."