1 Kings 2:22-24

King Solomon answered and said to his mother, “And why are you asking for Abishag the Shunammite for Adonijah? Ask the kingdom for him also—since he is my older brother—[ask it] for him and for Abiathar the priest and Joab the son of Zeruiah [his supporters]!” Then King Solomon swore by the LORD, saying, “May God do the same to me, and more also, if Adonijah has not requested this [deplorable] thing against his own life. So now, as the LORD lives, who has established me and set me on the throne of David my father, and who has made me a house as He promised, Adonijah shall indeed be put to death today.”