John Gill Bible Commentary

And Nathan said, my lord, O king,.... He addresses him as with great veneration and respect due to his office, so as if he knew noticing of Bathsheba's application to him; and therefore begins and tells his story, as if the king had never heard anything relative to it: hast thou said, Adonijah shall reign after me, and he shall sit upon my throne? surely it can never be, because of the notice which he himself had given him from the Lord, that one to be born should succeed him, plainly pointing to Solomon; and also because of the oath which he had sworn, to which Nathan was privy, that Solomon should reign after him; and yet if he had not given such orders, it was exceeding strange that Adonijah should presume to do what he had done.