Why did Jesus give Simon the "Rock" nickname as soon as he met him (without referring to Matthew 16)?

The most famous use of Peter/rock is **Matthew 16:18**: > And I say also unto thee, That thou art Peter, and upon this rock … But it was long before that, when Simon first met Jesus, that he was given the Peter/Cephas nickname in **John 1:42**: > … And when Jesus beheld him, he said, Thou art Simon the son of Jona: thou shalt be called Cephas, which is by interpretation, A stone. Without referring to the later events in Matthew 16, are there any published scholarly or doctrinal explanations for why Jesus gave Simon that particular nickname as soon as he met him? ## Note: - I'm not interested in explanations based on Matthew 16. - I'm not asking what *you* think is the reason.