1 Samuel 24:22

And David sware unto Saul,.... That he would not cut, off his posterity; which oath he religiously observed, in sparing Mephibosheth, 2 Samuel 21:7, and in punishing the murderers of Ishbosheth, 2 Samuel 4:12; and as for the seven sons of Saul, delivered up to the Gibeonites, 2 Samuel 21:6, it may be questioned whether they were his genuine legitimate offspring; and if they were, it was by the appointment and command of God, and according to his will and pleasure they were executed, who is not bound by the oaths of men, and to whom they must be submitted, 2 Samuel 21:1;

and Saul went home; to his palace in Gibeah:

but David and his men got them up unto the hold; in Engedi, 1 Samuel 23:29; not trusting to Saul, whose inconstancy, perfidy, cruel hatred, and malice, David full well knew; and therefore thought it not safe to return to his own house, nor to dwell in the open country, but in the wilderness, and among the rocks, and in the caves there, such as were in the wilderness of Engedi; and here, and at this time, he penned the fifty seventh psalm, see Psalms 57:1.