Charles Ellicott Commentary 1 Samuel 29:5

"Is not this David, of whom they sang one to another in dances, saying, Saul hath slain his thousands, And David his ten thousands?" — 1 Samuel 29:5 (ASV)

Of whom they sang. —The folk-songs, which had originally excited Saul’s jealousy of the young hero David, were current among the Philistines, who seem to have been a musical people. David’s having apparently learned and practised Philistine music when in Gath, which he subsequently introduced into Jerusalem, has been already noticed.