1 Kings 1:9-13

Adonijah invited all his brothers, the king's sons, and the king's officials of Judah, to come to the stone of Zoheleth, which is near En-rogel, where he sacrificed sheep, cattle and fattened calves.

But he didn't invite Nathan the prophet, Benaiah, David's bodyguard, or his brother Solomon.

Nathan went to Bathsheba, Solomon's mother, and asked her, “Haven't you heard that Adonijah, son of Haggith, has become king, and His Majesty King David doesn't even know?

Let me give you some advice so you can save your life, and that of your son Solomon.

Go immediately to King David and ask him, ‘Didn't Your Majesty swear to me, your servant, saying, Your son Solomon will definitely be king after me and will sit on my throne? So why is Adonijah saying he's king?’