John 21:18

Verily, verily, I say unto thee. — This phrase is peculiar to St. John. (Comp. Note on John 1:51.) The remainder of the verse contains three pairs of sentences answering to each other: —

“Thou wast young,”.... “Thou shalt be old;”
“Thou girdedst thyself,”.... “Thou shalt stretch forth thy hands, and another shall gird thee;”
“And walkedst whither thou wouldest,”... “And carry thee whither thou wouldest not.”

Thou wast young. — Literally, thou wast younger (than thou art now). Peter must have been at this time (comp. Matthew 8:14) in middle age.

Thou shalt stretch forth thy hands, and another shall gird thee. — Do these words refer to the crucifixion of Peter? Tradition, from Tertullian downwards (Scorp. xv.; De Praescr. xxxv.), states that he was crucified, and, interpreting this prophecy by the event, asserts that they do. Tertullian himself so understood them, for he says, “Then is Peter girded by another when he is bound to the cross.”

But on the other hand, (1) the girding (with chains) would precede, not follow, the crucifixion; (2) it would be more natural to speak of another stretching forth his hands if the nailing them to the cross is intended; (3) the last clause, “carry thee whither thou wouldest not,” could not follow the stretching of the hands on the transverse beam of the cross.
It seems impossible therefore to adopt the traditional reference to crucifixion, and we must take the words, “stretch forth thy hands,” as expressing symbolically the personal surrender previous to being girded by another. To what exact form of death the context does not specify. We have thus in the second pair of sentences, as in the first and third, a complete parallelism, the stretching forth of the hands being a part of the girding by another, and the whole being in contrast to “Thou girdedst thyself.”