23 Then king Solomon sware by Yahweh, saying, Elohim do so to me, and more also, if Adonijah have not spoken this word against his own life.

The Sin of Adonijah

—Adonijah was put to death because Solomon regarded his asking for Abishag as a re-assertion of his claim to the throne. Upon the occasion of his attempted usurpation, Solomon pardoned him on condition that he proved himself a worthy man (1 Sam. 1:5, 52).

He had now evidently lost all faith in him. If Adonijah's object was to re-open his assumed claim to the throne, or to get a footing in the royal house, the better to promote his plans; as Solomon's verdict seems to imply, then he was worthy of death. It was "the word" that Adonijah had spoken through Bathsheba that cost him his life.

The Christadelphian, Mar 1888