What are the cases in which the deceased is not prayed over?

The funeral prayer is a communal obligation (fard kifaya) upon every Muslim, including those who have committed major sins, and scholars have reached a consensus on this. The only exception is the martyr of the battlefield, as the Sunnah (definition) is not to pray over him. As for a miscarriage, if it is less than four months old, no prayer is offered over it because the soul has not yet been breathed into it. If it is more than four months old, then the prayer is offered over it. No prayer is offered over an apostate because he died in disbelief, nor over a hypocrite whose hypocrisy is known, due to Allah's saying: (And never pray over any of them who has died, nor stand by his grave. Indeed, they disbelieved in Allah and His Messenger and died while they were defiantly disobedient).