Albert Barnes Commentary 1 Kings 1:24

"And Nathan said, My lord, O king, hast thou said, Adonijah shall reign after me, and he shall sit upon my throne?" — 1 Kings 1:24 (ASV)

Have you said—You have said. In the original, no question is asked. Nathan assumes, by his wording, that the king has made this declaration. He wishes to elicit a denial.