1 Samuel 15:1-3

1 Samuel also said to Saul, The LORD sent me to anoint you to be king over his people, over Israel: now therefore listen you to the voice of the words of the LORD.

2 Thus said the LORD of hosts, I remember that which Amalek did to Israel, how he laid wait for him in the way, when he came up from Egypt.

3 Now go and smite Amalek, and utterly destroy all that they have, and spare them not; but slay both man and woman, infant and suckling, ox and sheep, camel and ass.