1 Kings 2:23-25

23Then King Solomon swore by the LORD: “May God punish me, and ever so severely, if Adonijah has not made this request at the expense of his life. 24And now, as surely as the LORD lives—the One who established me, who set me on the throne of my father David, and who founded for me a dynasty as He promised—surely Adonijah shall be put to death today!”

25So King Solomon gave orders to Benaiah son of Jehoiada, and he struck down Adonijah and he died.