1 Samuel 15:2-3

15:2 Thus saith 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. 15:3 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.