Truly, truly, I tell you [Peter], when you were young you used to fasten your belt around you [i.e., to get ready] and travel wherever you wanted to go. But when you are old, you will stretch out your hands and someone else will tie you up and take you [away] to where you do not want to go."

Now Jesus said this to indicate the kind of death Peter would experience in honoring God. [Note: Some see the "stretching out your hands," verse 18, as a reference to crucifixion]. And after saying this, Jesus said to him, "Be my follower."