Adam Clarke on Acts 15:22

Then pleased it the apostles and elders, with the whole Church - James determined what ought to be done; and the whole assembly resolved how that should be done.

Chosen men of their own company - Paul and Barnabas were to return: they could have witnessed to the Church at Antioch what was done at the council at Jerusalem; but as it was possible that their testimony might be suspected, from the part they had already taken in this question at Antioch, it was necessary that a deputation from the council should accompany them. Accordingly Judas and Silas are sent to corroborate by their oral testimony what was contained in the letters sent from the council.