Then David asked him, “To whom do you belong, and where are you from?” “I am an Egyptian,” he replied, “the slave of an Amalekite. My master abandoned me three days ago when I fell ill.
Solomon observes that the righteous is delivered out of trouble and the wicked cometh in his stead, that the just falleth seven times a-day and riseth again; so it was with David. Many were his troubles, but the Lord delivered him out of them all, and particularly out of this of which we have here an account. I.
Commenting on 1 Samuel 30:7-20
And David said unto him, to whom belongest thou?.... To what country or people? and to whom among them? and whence art thou? of what nation? where wast thou born? what countryman art thou? for his being called an Egyptian before seems to be by anticipation, unless it was guessed at by his habit; for until he had eaten and drank he could not speak...
My master left me, because three days agone I fell sick - This was very inhuman: though they had booty enough, and no doubt asses sufficient to carry the invalids, yet they left this poor man to perish; and God visited it upon them, as he made this very person the means of their destruction, by the information which he was enabled to give to David and his men.