Wa `alaykum As-Salamu wa Rahmatullahi wa Barakatuh

 

In the Name of Allah, the All-Merciful, the Mercy-Giving

 

All praise is due to Allah. Peace and blessings be upon His Messenger Muhammad.

 

I see no objection for him in lighting his father’s funeral pyre if required by the custom. It is the Hindu custom to cremate the dead; so he is only taking part in the funeral by doing it. However,  he should never associate it with an Islamic ritual.

 

Lighting the funeral fire is not the same as idol worship, which he cannot do as a Muslim.

 

Almighty Allah knows best.