What is the ruling on one who appears to people with a face different from what he is in reality, being good in front of some and bad in front of others (i.e., hypocrisy)?

Whoever appears before some people performing good deeds, and before others performing evil deeds, is considered among the worst of people. He is the two-faced person who comes to these with one face and to those with another. This is the characteristic of hypocrites who show something different from what they conceal, and they imagine that they are deceiving Allah and the believers.

If what this person conceals is disbelief (kufr), then he is a hypocrite of major hypocrisy (nifaq akbar), and his destiny is the lowest depth of the Hellfire, unless he repents, rectifies himself, holds fast to Allah, and dedicates his religion sincerely to Allah. His punishment in this world, if proven against him, is to be asked to repent three times. If he does not repent, the punishment for apostasy, which is execution, is carried out against him.

However, if what he conceals are sins short of disbelief, then he is in grave danger, and there is fear for him of gradually descending into major hypocrisy and dying upon disbelief. It is incumbent upon whoever knows his condition to advise him and guide him.