John Gill Commentary Acts 25:12

"Then Festus, when he had conferred with the council, answered, Thou hast appealed unto Caesar: unto Caesar shalt thou go." — Acts 25:12 (ASV)

Then Festus, when he had conferred with the council
Not with the Jewish sanhedrim, or any part of it that came down on this occasion; but with Roman counsellors, which he had to assist him in judgment, when any difficult matters were before him; the Syriac and Ethiopic versions render it, "with his counsellors"; and the Arabic reads in the singular number, "with his counsellor"; with these he advised, whether it was proper to admit of Paul's appeal, or not; and having had their opinion,

he answered, hast thou appealed unto Caesar? unto Caesar shalt thou
go :
the question is put, partly for the more certain knowledge of the thing, that there might be no mistake in it; and partly on account of the Jews, that they might see that though he was disposed to do them a favour, it was not in his power, because of this appeal; and it may be with some resentment in himself, since it carried in it a sort of reflection upon him, as if he was incapable of issuing this affair, or would not be just and faithful in it.