Adonijah hears that Solomon has been made king
Adonijah had finished feasting when he heard that Solomon had been anointed king, and had the support of David.
Key passages
1 Ki 1:41–49

And Adonijah and all the invited guests who were with him heard it. Now they were finished eating when Joab heard the sound of the trumpet and said, “Why is there such a noise in the city?” While he was still speaking, suddenly Jonathan the son …