Sheikh `Abd Allah al-Dumayjî
Whoever dies as an unbeliever is thereafter not entitled to our supplication on his behalf. We are not allowed to seek forgiveness or mercy for him.
Allah says: “It is not fitting for the Prophet and those who believe, that they should pray for forgiveness for the polytheists, even though they be of kin, after it is clear to them that they are companions of the Fire.” [Sûrah al-Tawbah: 113]
The Prophet (peace be upon him) asked Allah to allow him to seek forgiveness for his mother, who had already died. Allah allowed him to visit her grave but not to seek forgiveness for her.
It is permissible to offer supplications for guidance for a living unbeliever that his heart may accept Islam.
The Prophet (peace be upon him) said: “O Lord, support Islam by the most beloved `Umar to you.” This is a supplication for guidance for one of the two persons named `Umar to accept Islam. This took place just before `Umar b. al-Khattâb embraced Islam.
The Prophet (peace be upon him) said in another hadîth: “O Lord guide my people, they do not know (the true path)”
This is evidence that a Muslim can offer supplications for a non-Muslim while that non-Muslim is still alive.
The only prohibition is to offer a supplication for an unbeliever to receive forgiveness in the Hereafter if that person dies upon unbelief. This is the only thing prohibited by the sacred texts. There is no evidence to prohibit any other supplication on a non-Muslim’s behalf.
Therefore, we may also beseech Allah for a non-Muslim’s lawful worldly concerns – for instance, that the person has good health and other similar things related to prosperity in the world.
When we supplicate for the health and welfare of a non-Muslim, it is good to also supplicate for that person’s guidance.
And Allah knows best.
Source: Islam Today