Is he who said that the Prophet (peace be upon him) knows like the worms that dwell in filth an insulter of the Prophet (peace be upon him)? And what is the ruling on one who said this?

Comparing the Prophet, peace and blessings be upon him, to worms that inhabit filth is an insult and a denigration of him. The one who does this must repent, for denigrating the Messenger is a grave danger from which one fears apostasy for its perpetrator, as stated in the Almighty's saying: "Say, 'Is it Allah and His verses and His Messenger that you were mocking?' Make no excuse; you have disbelieved after your belief." However, passing judgment on a specific individual requires certain criteria.