1 Samuel 15:9 (KJV)

And Saul smote the Amalekites from Havilah until thou comest to Shur, that is over against Egypt.

And he took Agag the king of the Amalekites alive, and utterly destroyed all the people with the edge of the sword.

But Saul and the people spared Agag, and the best of the sheep, and of the oxen, and of the fatlings, and the lambs, and all that was good, and would not utterly destroy them: but every thing that was vile and refuse, that they destroyed utterly.

Then came the word of the Lord unto Samuel, saying,

It repenteth me that I have set up Saul to be king: for he is turned back from following me, and hath not performed my commandments. And it grieved Samuel; and he cried unto the Lord all night.