John Chrysostom — as excerpted in the Catena Aurea on Matthew 16:22-23

“For what wonder is it that this should befal Peter, who had never received a revelation concerning these things? For that you may learn that that confession which he made concerning Christ was not spoken of himself, observe how in these things which had not been revealed to him, he is at a loss. Estimating the things of Christ by human and earthly principles, he judged it mean and unworthy of Him that He should suffer. Therefore the Lord added, For thou savourest not the things that be of God, but the things that be of men.”