1 Samuel 15:14-18

But Samuel said, “What then is this bleating of the sheep in my ears, and the bellowing of the oxen which I hear?”

Saul said, “They have brought them from the Amalekites, for the people spared the best of the sheep and oxen to sacrifice to the Lord your God; but the rest we have completely destroyed.”

Then Samuel said to Saul, “Stop, and let me inform you of what the Lord said to me last night.” And he said to him, “Speak!”

So Samuel said, “Is it not true, though you were insignificant in your own eyes, that you became the head of the tribes of Israel? For the Lord anointed you as king over Israel.

And the Lord sent you on a mission, and said, ‘Go and completely destroy the sinners, the Amalekites, and fight against them until they are eliminated.’