18, 19. When thou wast young—embracing the whole period of life to the verge of old age.
thou girdedst thyself, and walkedst whither thou wouldest—wast thine own master.
when … old thou shalt stretch forth thine hands—to be bound for execution, though not necessarily meaning on a cross. There is no reason, however, to doubt the very early tradition that Peter's death was by crucifixion.