*Is it Permissible for a Muslim to Bury his Disbelieving Relative?*

 ‘Alee bin Abee Taalib (may Allaah be pleased with him) said: “I said to the Prophet (sallallaahu alayhi wasallam), ‘Your old, misguided uncle has died. Who will bury him?’ He said, ‘Go and bury your father’ (that is, ‘Alee may Allaah be pleased with him). He said, ‘I will not bury him, because he died as a disbeliever.’ He said, ‘Go and bury him, then do not do anything until you come to me.’ So I went and buried him, and came to him with traces of dust and earth on me. Then he instructed me to take bath, and he made supplication for me in words that were more pleasing to me than everything on earth.” 

Saheeh:  as-Saheehah, no. (161) 

Commenting on the above hadeeth, Shaykh al-Albaanee (may Allaah have mercy on him) said:

 1 - It is legislated for a Muslim to attend to the burial of his disbelieving relative. And that does not negate his hatred of him due to his shirk. Do you not see that ‘Alee (may Allaah be pleased with him) initially refused to bury his father and the reason he gave for that as contained in his saying was that: ‘He died as a disbeliever;’ he thought that burying him as a disbeliever may include him in the forbidden friendship that was mentioned in the saying of the Most High: “Take not as friends the people who incurred the Wrath of Allaah…”[1] When the Prophet (sallallaahu alayhi wasallam) reiterated the command to bury his father, he hastened to comply to it and he abandoned what he initially thought [to be correct]. This is what obedience means: that an individual abandons his opinion for the command of his Prophet (sallallaahu alayhi wasallam).

It seems to me that a son burying his disbelieving father or mother is the last of what a son can do of good companionship for his disbelieving parent in this world. But after the burial, it is not right for him to make supplication for them or pray for forgiveness for them , due to the explicit words of Allaah exalted: It is not (proper) for the Prophet and those who believe to ask Allaah’s Forgiveness for the Mushrikûn (polytheists, idolaters, pagans, disbelievers in the Oneness of Allaah) even though they be of kin...”[2] If the issue is like this, what would be the case of those who pray for mercy and forgiveness in the pages of newspapers and magazines for some disbelievers, in death announcements for the sake of meagre amount of money? Let the one who has concern for the affair of his hereafter fear Allaah. 

2 – It is not legislated for him to wash or shroud a disbeliever, or to perform the funeral prayer over him, even if he was his relative, because the Prophet (sallallaahu alayhi wasallam) did not enjoin that on ‘Alee. If that were permissible, the Prophet (sallallaahu alayhi wasallam) would have explained it, because it is well known that delaying the explanation of something at the time of need is not permissible. This is the view of the Hanbalee school of though and others. 

3 – It is not legislated for the relatives of a disbeliever to follow his funeral, because the Prophet (sallallaahu alayhi wasallam) did not do that with his uncle, despite the fact that he was the most kind and compassionate of mankind towards him, and he even supplicated to Allaah for him that He should make his punishment the lightest punishment in Hell as explained previously in hadeeth no. 53. 

In all of that, there is a lesson for those who are beguiled by their lineages and do not work for their Hereafter with their Lord. Allaah the Most Great spoke the truth when He said: “…There will be no kinship among them that Day, nor will they ask of one another.”[3]

Source: Nudhum al-Faraa’id mimma fee Silsilati al-Albaanee min Fawaa’id, vol. 1, p. 481-482 by Abdul-Lateef bin Muhammad bin Ahmad bin Abee Rabee

Does he not have his own family?
His burial rites should be according to his desire which I guess he must have shared with them. Perhaps he doesn't want to be buried under Islamic rites.