1 Samuel 15:9-11 NIV
But Saul and the army spared Agag and the best of the sheep and cattle, the fat calves and lambs—everything that was good. These they were unwilling to destroy completely, but everything that was despised and weak they totally destroyed.
Then the word of the LORD came to Samuel: “I regret that I have made Saul king, because he has turned away from me and has not carried out my instructions.” Samuel was angry, and he cried out to the LORD all that night.
NIV: New International Version