8 Now David and his men went up and made raids against the Geshurites, the Girzites, and the Amalekites, for these were the inhabitants of the land from of old, as far as Shur, to the land of Egypt. 9 And David would strike the land and would leave neither man nor woman alive, but would take away the sheep, the oxen, the donkeys, the camels, and the garments, and come back to Achish. 10 When Achish asked, "Where have you made a raid today?" David would say, "Against the Negeb of Judah," or, "Against the Negeb of the Jerahmeelites," or, "Against the Negeb of the Kenites." 11 And David would leave neither man nor woman alive to bring news to Gath, thinking, "lest they should tell about us and say, 'So David has done.'" Such was his custom all the while he lived in the country of the Philistines. 12 And Achish trusted David, thinking, "He has made himself an utter stench to his people Israel; therefore he shall always be my servant."
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.