Adam Clarke on 1 Samuel 29:10

With thy master's servants - Who were these? has been very properly asked; and to this question there can be but two answers: -

1. The six hundred Israelites which were with him; and who might still be considered the subjects of Saul, though now residing in a foreign land.

2. The servants of achish; i.e., David's men thus considered; because on his coming to Gath, he had in effect given up himself and his men to Achish. But Saul may be the master to whom Achish refers, and the words convey a delicate information to David that he is no vassal, but still at liberty.