Charles Ellicott Commentary 1 Samuel 27:10

"And Achish said, Against whom have ye made a raid to-day? And David said, Against the South of Judah, and against the South of the Jerahmeelites, and against the South of the Kenites." — 1 Samuel 27:10 (ASV)

And David said, Against the south of Judah. — The answer of David to his sovereign lord, the King of Gath—for he was now, to all intents and purposes, a vassal prince of Achish—was simply a falsehood. He had been engaged in distant forays against the old Bedouin enemies of Israel, far away in the desert which stretched to the frontier of Egypt. And from these nomads—rich in cattle and in other property, which they had obtained by years of successful plunder—he seems to have gained much booty, a share of which he brought to his “suzerain,” Achish.

But David represents that the cattle and apparel had been captured from his own countrymen, whose territory he was harrying. “The Jerahmeelites were descendants of Jerahmeel, the firstborn of Hezron (1 Chronicles 2:9; 1 Chronicles 2:25–26), and therefore one of the three large families of Judah who sprang from Hezron.”— Keil, They lived, it is believed, on the southern frontier of the tribe of Judah. The Kenites were a race living in friendship with and under the protection of Judah.