1 Samuel 15: 16 - 23
16 Then Samuel said to Saul, "Stop! I will tell you what the LORD said to me this night." And he said to him, "Say on."
17 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.
18 And the LORD sent you on a mission, and said, `Go, utterly destroy the sinners, the Amal'ekites, and fight against them until they are consumed.'
19 Why then did you not obey the voice of the LORD? Why did you swoop on the spoil, and do what was evil in the sight of the LORD?"
20 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 Am'alek, and I have utterly destroyed the Amal'ekites.
21 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."
22 And Samuel said, "Has the LORD as great delight in burnt offerings and sacrifices, as in obeying the voice of the LORD? Behold, to obey is better than sacrifice, and to hearken than the fat of rams.
23 For rebellion is as the sin of divination, and stubbornness is as iniquity and idolatry. Because you have rejected the word of the LORD, he has also rejected you from being king."

EWTN