Ambrose of Milan — as excerpted in the Catena Aurea on Matthew 11:1-6

“(in Luc. 7. 19.) Some understand it thus; That it was a great thing that John should be so far a prophet, as to acknowledge Christ, and to preach remission of sin; but that like a pious prophet, he could not think that He whom he had believed to be He that should come, was to suffer death; he doubted therefore though not in faith, yet in love. So Peter also doubted, saying, This be far from thee, Lord; this shall not be unto thee. (Mat. 16:22.)”