1 Samuel 15:17-19

And Samuel told him, “Although you may think little of yourself, are you not the leader of the tribes of Israel? The LORD has anointed you king of Israel. And the LORD sent you on a mission and told you, ‘Go and completely destroy the sinners, the Amalekites, until they are all dead.’ Why haven’t you obeyed the LORD? Why did you rush for the plunder and do what was evil in the LORD’s sight?”