151 Samuel said to Saul, "God sent me to anoint you king over his people, Israel. Now, listen again to what God says. 2 This is the God-of-the-Angel-Armies speaking: 3 Here's what you are to do: Go to war against Amalek. Put everything connected with Amalek under a holy ban. And no exceptions! This is to be total destruction - men and women, children and infants, cattle and sheep, camels and donkeys - the works.'" 4 Saul called the army together at Telaim and prepared them to go to war - two hundred companies of infantry from Israel and another ten companies from Judah. 5 Saul marched to Amalek City and hid in the canyon. 6 Then Saul got word to the Kenites: "Get out of here while you can. Evacuate the city right now or you'll get lumped in with the Amalekites. I'm warning you because you showed real kindness to the Israelites when they came up out of Egypt." And they did. The Kenites evacuated the place.
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.