1 Samuel (Author Compiled by Isaiah from records of Samuel, David, Nathan, and Gad.)
15:20And Saul said unto Samuel, Yea, I have obeyed the voice of the LORD, and have gone the way which the LORD sent me, and have brought Agag the king of Amalek, and have utterly destroyed the Amalekites.
Original from The Bible Foundation - bf.org. They claim public domain status for their original text.