What is the ruling of Islamic law on attending the funerals of disbelievers, which has become a political tradition and an agreed-upon custom?

If there are disbelievers who bury their dead, Muslims are not to bury them or participate in their burial, as Allah says: (And never (O Muhammad صلى الله عليه وسلم) pray (funerary prayer) for anyone of them who dies, nor stand by his grave. Certainly, they disbelieved in Allah and His Messenger, and died while they were Fasiqun (rebellious, disobedient to Allah and His Messenger صلى الله عليه وسلم)). However, if there is no one among them to bury the dead, it is permissible for Muslims to bury them, as the Prophet (peace be upon him) did with the slain at Badr, and his command to Ali to bury Abu Talib.