1 Samuel 15:20-21

20“But I did obey the voice of Adonai,” Saul said to Samuel. “I went on the mission on which Adonai sent me, and brought back Agag the king of Amalek—and utterly destroyed the Amalekites.

21But the people took some of the spoil, sheep and oxen—the best of what was under the ban of destruction— to sacrifice to Adonai your God in Gilgal.”