1 Samuel 15
Saul was instructed by the Lord to go and completely destroy the wicked Amalekites, wiping them out entirely, even all their livestock. But Saul and his army spared the Amalekite king and the best of their sheep and catttle-- "these they were unwilling to destroy". Samuel was angry when he learned that Saul had violated the Lord's instructions. Samuel rebuked Saul for his rebellion and arrogance. Samuel told Saul that the Lord has now "torn the kingdom of Israel from you and has given it to one of your neighbors--to one better than you".