I Kings 2:15, 22-24

Then he said, “You know that the kingdom was mine, and all Israel had set their expectations on me, that I should reign. However, the kingdom has been turned over, and has become my brother’s; for it was his from the LORD.

And King Solomon answered and said to his mother, “Now why do you ask Abishag the Shunammite for Adonijah? Ask for him the kingdom also—for he is my older brother—for him, and for Abiathar the priest, and for Joab the son of Zeruiah.” Then King Solomon swore by the LORD, saying, “May God do so to me, and more also, if Adonijah has not spoken this word against his own life! Now therefore, as the LORD lives, who has confirmed me and set me on the throne of David my father, and who has established a house for me, as He promised, Adonijah shall be put to death today!”