The further element in Nathan’s plan as he advised Bathsheba was the part of it that he planned to execute. He said that he would come into the king’s presence while she was still there speaking with David. He said this would be to confirm what she was telling the king.
We might ask what particular in her speech needed confirmation. Since, David had sworn the oath to Bathsheba concerning Solomon’s reign after him, that portion of Bathsheba’s speech did not need confirmation. Indeed, as the narrative unfolds in the text, Nathan said nothing about David’s oath as he spoke to the king.
We may ask why Nathan thought a confirmation was necessary. The news that Adonijah had made himself king without David’s knowledge and permission constituted an accusation of the crimes of rebellion and treason. The law required that accusations of crimes should be attested by at least two witnesses. Nathan, therefore, proceeded according to the commandments of God in his law.
The matter that needed confirmation was the news that Adonijah made himself king. The language of this verse is straightforward and scarcely needs any comment. Beyond that, all that was needed was that they put the plan into operation, and that brings us to the following verse.
14 Then while you are still speaking with the king, I also will come in after you and confirm your words.”