John Gill Commentary Genesis 32:27

"And he said unto him, What is thy name? And he said, Jacob." — Genesis 32:27 (ASV)

And he said to him, what [is] your name ?
&c.] Which question is put, not as being ignorant of it, but in order to take occasion from it, and the change of it, to show that he had granted his request, and had blessed him, and would yet more and more: and he said, Jacob ;
the name given him at his birth, and by which he has always been called, and therefore tells it to him at once, not waiting to ask the reason of the question.