8 David and his men went up, and made a raid on the Geshurites, and the Girzites, and the Amalekites; for those nations were the inhabitants of the land, who were of old, as you go to Shur, even to the land of Egypt. 9 David struck the land, and saved neither man nor woman alive, and took away the sheep, and the cattle, and the donkeys, and the camels, and the clothing; and he returned, and came to Achish. 10 Achish said, “Against whom have you made a raid today?”
David said, “Against the South of Judah, against the South of the Jerahmeelites, and against the South of the Kenites.” 11 David saved neither man nor woman alive, to bring them to Gath, saying, “Lest they should tell of us, saying, ‘So did David, and so has been his manner all the while he has lived in the country of the Philistines.’” 12 Achish believed David, saying, “He has made his people Israel utterly to abhor him. Therefore he shall be my servant 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.