John Calvin on John 20:8

8. And he saw and believed. It is a poor exposition which some give of these words, that John believed what he had heard Mary say, namely, that Christ’s body had been carried away; for there is no passage in which the word believe bears this meaning, especially when it is used simply and without any addition. Nor is this inconsistent with the fact, that Peter and John return home, while they are still in doubt and perplexity; for in some passages John had employed this phraseology, when lie intended to describe the increase of faith. Besides, Luke 24:12 relates that Peter wondered at seeing the sepulcher in such good order; meaning by this, that Peter thought of something greater and loftier than what Mary had told him.