Is it permissible to pray over someone known for committing sins such as smoking, shaving his beard, and dealing in usury, and if it is not permissible, what should be done?

Praying over a deceased Muslim is a communal obligation (fard kifaya). People who have committed sins are prayed over like all other Muslims. Muslims have unanimously agreed on the permissibility of praying over sinners and those who have committed major sins, based on the Prophet's (peace be upon him) saying: "Pray over everyone who says 'There is no god but Allah, and Muhammad is the Messenger of Allah.'"

An exception to this is that the Imam, or someone in a similar position, may not pray over certain individuals who committed major sins, such as one who embezzles from war booty (al-ghall) or one who commits suicide. This is to deter people and warn them against committing such sins. However, this does not prevent other Muslims from praying over them.