Acts 23
12 And when it was day, some of the Jews banded together and bound themselves under an oath, saying that they would neither eat nor drink till they had killed Paul. 13 Now there were more than forty who had formed this conspiracy. 14 They came to the chief priests and elders, and said, “We have bound ourselves under a great oath that we will eat nothing until we have killed Paul. 15 Now you, therefore, together with the council, suggest to the commander that he be brought down to you [c]tomorrow, as though you were going to make further inquiries concerning him; but we are ready to kill him before he comes near.”

So this plot to kill Paul included the chief priests and the elders. Everyone is dirty.
They took an oath not to eat or drink until they have killed Paul. This oath seems unnecessary. Just kill Paul if that is your desire.

Something else I noticed, is the plan isn’t until tomorrow. So all today they will NOT eat, or drink.  That means they have a full day to be angry, and ready to end Paul quickly so they can eat and drink and be merry.