1 Samuel 15:18-20

and the LORD sent you on a mission, and said, ‘Go and utterly destroy the sinners, the Amalekites, and fight against them until they are exterminated.’ Why then did you not obey the voice of the LORD, but rushed upon the spoil and did what was evil in the sight of the LORD?” Then Saul said to Samuel, “I did obey the voice of the LORD, and went on the mission on which the LORD sent me, and have brought back Agag the king of Amalek, and have utterly destroyed the Amalekites.