All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallahu ʻalayhi wa sallam, is His slave and Messenger.
First of all, we praise Allah for guiding you to Islam, and we ask Him to bless you and comfort your heart with guiding your parents and the rest of your family to Islam. Whoever of them dies while adhering to their false religion, you may follow their funeral procession without joining the funeral prayer offered for them or supplicating Allah in their favor. A group of scholars held that it is permissible to follow the funeral procession of a non-Muslim relative, and some reports were narrated on the authority of the Companions in this regard. In the following lines, we will mention some of them:
An-Nawawi said, “As for offering funeral prayer over a disbeliever or supplicating Allah to forgive him, it is prohibited by the text of the Quran and the consensus of scholars ... and it is permissible for the Muslim to follow the funeral procession of his non-Muslim relative...” [Al-Majmoo’]
Ibn Al-Qayyim said in his book Ahkaam Ahl Ath-Thimmah (Rulings relevant to non-Muslims in Muslim Lands):
“Chapter on attending their funerals: Muhammad ibn Moosa said, ‘I asked Abu ʻAbdullah (meaning Imam Ahmad ibn Hanbal), 'Does a Muslim attend the funeral procession of a non-Muslim?' He said, 'Yes.'’
Muhammad ibn Al-Hasan ibn Haaroon said, ‘‘Abu ʻAbdullah (Imam Ahmad) was asked, 'And he (the Muslim) attends the funeral of a non-Muslim?' He replied, 'Yes, as did Al-Haarith ibn Abi Rabeeʻah; he attended the funeral of his (non-Muslim) mother. He attended the funeral of his mother and he kept to the side...' Abu Taalib said, 'I asked Abu ʻAbdullah about a man who died as a Jew leaving behind a Muslim son; what should the son do? He replied, ‘He rides his mount in front of the funeral procession, and he should not be behind him. When they are about to bury him, he leaves, just as ʻUmar said.’' I say: He meant what was narrated by Saʻeed ibn Mansoor ... Abu Waa'il said, 'My Christian mother passed away; I went to ʻUmar and asked him (what to do), and he replied, ‘Ride in her funeral procession and be in front of her.’'’
Hanbal said, ‘I asked Abu ʻAbdullah about a Muslim whose Christian mother, father, brother, or relative passes away; is he allowed to handle any part of his funeral until he buries him? He replied, 'If this non-Muslim is a father, mother, brother, or a close relative, and he attended it, then there is no harm in that. The Prophet, sallallahu ʻalayhi wa sallam, commanded ʻAli ibn Abi Taalib, may Allah be pleased with him, to bury (his non-Muslim father) Abu Taalib.' I said, 'Do you believe that he (the Muslim asked about) should do the same?' He said, 'The followers of his religion handle his body, and the Muslim relative is present with them until they take it (for burial), he then leaves them and they bury him. Saalih ibn Ahmad said, ‘I asked my father (Imam Ahmad), 'A Muslim man whose Christian mother passed away; does he follow her funeral procession?' He replied, 'He walks to the side of the procession.'’' Saʻeed ibn Mansoor said that Sufyaan narrated on the authority of Abu Sinaan from Saʻeed ibn Jubayr that he said, 'I asked Ibn ʻAbbaas, may Allah be pleased with him, about a man whose father died as a Christian, and he said, ‘He attends the funeral and buries him.’'’” [Ahkaam Ahl Ath-Thimmah]
The Fatwa of the Permanent Committee for Iftaa' reads:
“It is incumbent on you to be dutiful to your parents, even if they are non-Muslims, and to accompany them in the life of this world with kindness by providing for them, clothing them, treating them kindly and compassionately, speaking to them gently, calling them to Islam with wisdom and good advice, and guiding them to the signs of the truth. Hopefully Allah would guide them to Islam. If either of them refuses to embrace Islam, there is no objection that you bury him yourself and to do what is necessary in this regard without performing the funeral prayer over them or supplicating Allah for them, and without partaking in any religious innovations practiced by the followers of the deceased's false religion regarding their rituals in funerals, burials, and what follows that of sinful practices.”
Allah knows best.