'Serve' in the Bible

So Mephibosheth the son of Jonathan, the son of Saul, came to David. And he fell on his face and did obeisance. David said, "Mephibosheth," and he said, "{I am ready to serve you}."

{Furthermore}, for whom have I served? [Is] it not in the presence of his son that I have served before your father? {So shall I serve you}!"