What does John 5:15 mean?
The Bible does not include every possible detail about every story. The man Jesus has healed might have expressed some gratitude to Jesus. He might not have. However, putting the various details together doesn't paint an optimistic picture. Jesus seems to have been questioning whether or not the man was really interested in healing (John 5:6). The formerly crippled man, for his part, seems more apt to complaining (John 5:7) and shifting the blame (John 5:11) than anything else.This same man was interrogated by local religious leaders for carrying his bed on the Sabbath. Even when he told them he'd been healed, their primary concern was still their Sabbath traditions (John 5:12). Now that the man knows who Jesus is, he goes and tells the men who'd confronted him about the source of his cure.
As the next verse shows, the amazing instance of healing is totally lost on these hard-hearted men. Every mention of Jesus, from the perspective of the religious authorities, relates to the Sabbath, not the miracle (John 5:10, 12, 16, 18).