8 David and his men spent their time raiding the Geshurites, the Girzites, and the Amalekites-people who had lived near Shur, toward the land of Egypt, since ancient times. 9 David did not leave one person alive in the villages he attacked. He took the sheep, goats, cattle, donkeys, camels, and clothing before returning home to see King Achish. 10 "Where did you make your raid today?" Achish would ask. And David would reply, "Against the south of Judah, the Jerahmeelites, and the Kenites." 11 No one was left alive to come to Gath and tell where he had really been. This happened again and again while he was living among the Philistines. 12 Achish believed David and thought to himself, "By now the people of Israel must hate him bitterly. Now he will have to stay here and serve me forever!"

Matthew Henry's Commentary on 1 Samuel 27:8-12

Commentary on 1 Samuel 27:8-12

(Read 1 Samuel 27:8-12)

While David was in the land of the Philistines, he attacked some remains of the devoted nations. The people whom he cut off were long before doomed to destruction. It is often wisdom to shun public notice, but we must in no situation be idle. We must always try to do somewhat in the cause of God. This expedition David hid from Achish. But an equivocation which serves the purpose of a lie, is as like to it as a hypocrite is to a profane person, it is only better in appearance, therefore more dangerous. Yet, though believers often manifest imperfections, they can never be prevailed upon to renounce the service of God, and to unite interests with his enemies, or finally to become the servants of sin and Satan. But what a train of evils follow from unbelief! When we forget the Lord's past mercies, and his gracious assurances, we shall be overwhelmed with desponding fears, and probably be led to adopt some dishonourable method to get rid of our troubles. Nothing can so effectually establish us in holy tempers and practices, and preserve us from perplexities, as firm, unshaken dependence upon the promises of God in Christ Jesus.