What is the religious ruling regarding a young man who loves his father, who was disobedient to his own parents and hates to pray for mercy upon them? Will the son suffer the same fate as his father inflicted upon his parents? And what is the son's fault in bearing the punishment of his father who mistreats him?

It is not permissible for a child to disobey his father on the pretext that his father was disobedient to his own parents. Rather, the child must honor him and treat him kindly. There is no necessary connection between a father's disobedience to his father and a son's disobedience to him. The hadith reported regarding this is weak. Disobedience to parents is a grave matter, but this does not justify a son's disobedience to his father. Allah Almighty will question each of them about the dutifulness they owed to their own parents. A father's harshness towards his son is not a justification for disobedience. Allah Almighty commanded honoring parents in all circumstances, except in disobedience to Allah.