151 And Samuel said to Saul, Jehovah sent me to anoint thee king over his people, over Israel: now therefore hearken to the voice of the words of Jehovah. 2 Thus saith Jehovah of hosts: I have considered what Amalek did to Israel, how he set himself against him in the way, when he came up from Egypt. 3 Now go and smite Amalek, and destroy utterly all that they have, and spare them not, but slay both man and woman, infant and suckling, ox and sheep, camel and ass. 4 And Saul summoned the people, and numbered them in Telaim, two hundred thousand footmen, and ten thousand men of Judah. 5 And Saul came to the city of the Amalekites, and set an ambush in the valley. 6 And Saul said to the Kenites, Go, depart, and go down from among the Amalekites, lest I destroy you with them; for ye shewed kindness to all the children of Israel when they came up out of Egypt. And the Kenites departed from among the Amalekites.
Matthew Henry's Commentary on 1 Samuel 15:1-6
Commentary on 1 Samuel 15:1-9
(Read 1 Samuel 15:1-9)
The sentence of condemnation against the Amalekites had gone forth long before, Revelation 18:4. As the commandment had been express, and a test of Saul's obedience, his conduct evidently was the effect of a proud, rebellious spirit. He destroyed only the refuse, that was good for little. That which was now destroyed was sacrificed to the justice of God.