Is the foul odor emanating from the grave of a man known for his cruelty and advocacy of secularism evidence of his bad end?

We have not found an explicit text stating that a smell emanating from the grave is a sign of a bad ending. However, Sheikh Ahmed Farid, in stories of bad endings after burial, mentioned the rejection of the deceased from his grave or his grave turning into fire. The emission of a foul smell could be one of the signs of this, or it could have another cause, such as the grave not being deep enough. Supporting the wicked and evil people against those who invite to Allah is forbidden, and harshness towards relatives is not among the characteristics of believers. The Prophet, peace and blessings be upon him, said, "Those are not the best among you" concerning those who beat their wives, and "The best among you are those who are best to their families." So, whoever dies in this state is not successful, and prayer should be made for him if he died upon Islam.