John Gill Commentary 1 Samuel 30:13

"And David said unto him, To whom belongest thou? and whence art thou? And he said, I am a young man of Egypt, servant to an Amalekite; and my master left me, because three days ago I fell sick." — 1 Samuel 30:13 (ASV)

And David said unto him, to whom [belongest] thou ?
&c.] 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, and so could not be known by his speech:

for he said, I [am] a young man of Egypt ;
that was the country he belonged to, and came from; he was an Egyptian by birth:

servant to an Amalekite ;
one of those that had invaded the country, and burnt Ziklag, as it follows:

and my master left me, because three days agone I fell sick ;
which was very barbarous and cruel to leave him at all, when they had camels with them, (1 Samuel 30:17) ; and no doubt carriages for their arms, provision, and spoil, and men; and more so to leave him without anybody with him to take care of him, and without any food, when he capable of eating any; but so it was ordered by the providence of God, that should be left to be the instrument of the just ruin of his master, and of the whole troop.