Behold, to obey is better than sacrifice, And to heed than the fat of rams.

So Samuel said, “.....Now the Lord sent you on a mission, and said, ‘Go, and utterly destroy 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 swoop down on the spoil, and do evil in the sight of the Lord ?” And Saul said to Samuel, “But I have obeyed the voice of the Lord, and gone on the mission on which the Lord sent me, and brought back Agag king of Amalek; I have utterly destroyed the Amalekites. But the people took of the plunder, sheep and oxen, the best of the things which should have been utterly destroyed, to sacrifice to the Lord your God in Gilgal.” So 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 heed than the fat of rams. For rebellion is as the sin of witchcraft, And stubbornness is as iniquity and idolatry. Because you have rejected the word of the Lord, He also has rejected you from being king.” Then Saul said to Samuel, “I have sinned, for I have transgressed the commandment of the Lord and your words, because I feared the people and obeyed their voice. Now therefore, please pardon my sin, and return with me, that I may worship the Lord.” But Samuel said to Saul, “I will not return with you, for you have rejected the word of the Lord, and the Lord has rejected you from being king over Israel.” And as Samuel turned around to go away, Saul seized the edge of his robe, and it tore. So Samuel said to him, “The Lord has torn the kingdom of Israel from you today, and has given it to a neighbor of yours, who is better than you. And also the Strength of Israel will not lie nor relent. For He is not a man, that He should relent.”
1 Samuel 15:17-29 - NKJV