1 Samuel 15:16-18

16Then Samuel said to Saul, “Be quiet! And I will tell you what the Lord said to me last night.” And he said to him, “Speak on.”

17So Samuel said, “When you were little in your own eyes, were you not head of the tribes of Israel? And did not the Lord anoint you king over Israel?

18Now the Lord sent you on a mission, and said, ‘Go, and utterly destroy the sinners, the Amalekites, and fight against them until they are consumed.’