1 Samuel 15:7-22 ESV
And Saul defeated the Amalekites from Havilah as far as Shur, which is east of Egypt. And he took Agag the king of the Amalekites alive and devoted to destruction all the people with the edge of the sword. But Saul and the people spared Agag and the best of the sheep and of the oxen and of the fattened calves and the lambs, and all that was good, and would not utterly destroy them. All that was despised and worthless they devoted to destruction.
The word of the LORD came to Samuel: “I regret that I have made Saul king, for he has turned back from following me and has not performed my commandments.” And Samuel was angry, and he cried to the LORD all night. And Samuel rose early to meet Saul in the morning. And it was told Samuel, “Saul came to Carmel, and behold, he set up a monument for himself and turned and passed on and went down to Gilgal.” And Samuel came to Saul, and Saul said to him, “Blessed be you to the LORD. I have performed the commandment of the LORD.” And Samuel said, “What then is this bleating of the sheep in my ears and the lowing of the oxen that I hear?” Saul said, “They have brought them from the Amalekites, for the people spared the best of the sheep and of the oxen to sacrifice to the LORD your God, and the rest we have devoted to destruction.” Then Samuel said to Saul, “Stop! I will tell you what the LORD said to me this night.” And he said to him, “Speak.”
And Samuel said, “Though you are little in your own eyes, are you not the head of the tribes of Israel? The LORD anointed you king over Israel. And the LORD sent you on a mission and said, ‘Go, devote to destruction the sinners, the Amalekites, and fight against them until they are consumed.’ Why then did you not obey the voice of the LORD? Why did you pounce on the spoil and do what was evil in the sight of the LORD?” And Saul said to Samuel, “I have obeyed the voice of the LORD. I have gone on the mission on which the LORD sent me. I have brought Agag the king of Amalek, and I have devoted the Amalekites to destruction. But the people took of the spoil, sheep and oxen, the best of the things devoted to destruction, to sacrifice to the LORD your God in Gilgal.” And Samuel said
ESV: English Standard Version 2016