Charles Ellicott Commentary 1 Samuel 15:3

"Now go and smite Amalek, and utterly destroy all that they have, and spare them not; but slay both man and woman, infant and suckling, ox and sheep, camel and ass." — 1 Samuel 15:3 (ASV)

Smite Amalek, and utterly destroy ... —For “utterly destroy,” the Hebrew has the far stronger expression, “put under the ban” (cherem). Whatever was “put under the ban” in Israel was devoted to God, and whatever was so devoted could not be redeemed, but must be slain. Amalek was to be looked upon as accursed; human beings and cattle must be killed; whatever was capable of being destroyed by fire must be burnt. The cup of iniquity in this people was filled up. Its national existence, if prolonged, would simply have worked mischief to the commonwealth of nations.

Israel here was simply the instrument of destruction used by the Almighty. It is vain to attempt in this and similar transactions to find materials for the blame or the praise of Israel. We must never forget that Israel stood in a peculiar relation to the unseen King, and that this nation was often used as the visible scourge by which the All-Wise punished hopelessly hardened sinners, and deprived them of the power of working mischief. We might as well find fault with pestilence and famine, or the sword—those awful instruments of Divine justice and—though we often fail to see it now—of Divine mercy.