In the first Book of Samuel, the prophet delivers a clear command from God to King Saul: Utterly destroy the Amalekites, a vicious enemy of Israel, and leave nothing alive — not man, woman, child, or beast. Saul obeys in part, routing their army, but when he captures King Agag, he spares the tyrant’s life out of misplaced mercy. The prophet Samuel confronts the king in fury, then executes Agag himself. Rabbinic tradition records the devastating aftermath: Agag’s lineage survives, eventually producing Haman, the Persian vizier who plots the first attempted genocide of the Jewish people in the Book of Esther. From this episode, the sages distilled a timeless warning: “He who is merciful when he must be cruel will be cruel when he must be merciful.”