John Gill Commentary 2 Samuel 1:13

"And David said unto the young man that told him, Whence art thou? And he answered, I am the son of a sojourner, an Amalekite." — 2 Samuel 1:13 (ASV)

And David said to the young man that told him, from where [are]
you ?
&c.] From what place, or of what people and nation are you? though Abarbinel thinks it neither respects place nor people, but that David thought he was another man's servant; so that the sense of the question is, to what man did he belong?

and he answered, I [am] the son of a stranger, an Amalekite ;
he was not any man's servant, but the son of a proselyte, of one that was by birth and nation an Amalekite, but proselyted to the Jewish religion; he might know of what nation he originally was, by the account he had given of what passed between him and Saul, (2 Samuel 1:8) ; though the mind of David might so disturbed as not to advert to it; or if he did, he might be willing to have it repeated for confirmation's sake.