1 Kings 2:21-25

21So she said, “Let Abishag the Shunammite be given to your brother Adonijah as a wife.”

22King 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]!”

23Then 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.

24So 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.”

25So King Solomon sent Benaiah the son of Jehoiada, and he struck Adonijah and he died.