151 And Samuel said to Saul, "The Lord sent me to anoint you king over his people Israel; now therefore hearken to the words of the Lord. 2 Thus says the Lord of hosts, 'I will punish what Am'alek did to Israel in opposing them on the way, when they came up out of Egypt. 3 Now go and smite Am'alek, and utterly destroy all that they have; do not spare them, but kill both man and woman, infant and suckling, ox and sheep, camel and ass.'" 4 So Saul summoned the people, and numbered them in Tela'im, two hundred thousand men on foot, and ten thousand men of Judah. 5 And Saul came to the city of Am'alek, and lay in wait in the valley. 6 And Saul said to the Ken'ites, "Go, depart, go down from among the Amal'ekites, lest I destroy you with them; for you showed kindness to all the people of Israel when they came up out of Egypt." So the Ken'ites departed from among the Amal'ekites.
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.