1 Samuel 15:18 KJV
And the Lord sent thee on a journey, and said, Go and utterly destroy the sinners the Amalekites, and fight against them until they be consumed.
1 Samuel 15:18, King James Version
In context
17 And Samuel said, When thou wast little in thine own sight, wast thou not made the head of the tribes of Israel, and the Lord anointed thee king over Israel?
18 And the Lord sent thee on a journey, and said, Go and utterly destroy the sinners the Amalekites, and fight against them until they be consumed.
19 Wherefore then didst thou not obey the voice of the Lord, but didst fly upon the spoil, and didst evil in the sight of the Lord?