Is it permissible to make Dua for non Muslim ?
What is the ruling regarding making dua that the punishment becomes lightened for a disbeliever? Answer: ﺑﺴﻢ اﷲ اﻟﺮﺣﻤﻦ اﻟﺮﺣﯿﻢ In the name of Allah, the Most Gracious, the Most Merciful
It is not permissible to make dua for a unbeliever after their demise, e.g. asking Allah ﺗﻌﺎﻟﻰ to forgive them, lessen their punishment, etc.  The evidence for this can be found in the Quran where Allah ﺗﻌﺎﻟﻰ says, “And it is not (lawful) for the Prophet and for those who believe to seek forgiveness for the polytheists, even if they are relatives, after it has become clear to them that they are the people of Hell.” (Surah Taubah: v. 113) In addition, Allah ﺗﻌﺎﻟﻰ has informed us in the Quran that the punishment will not be lightened for the disbelievers, hence one should not ask Him to do something which He has promised he will not do ; Allah ﺗﻌﺎﻟﻰ says, “The punishment will not be lightened for them, nor will they be given respite.” (Surah Baqarah: v. 162). Nevertheless, one may make dua for the unbelievers whilst they are living, e.g. asking Allah ﺗﻌﺎﻟﻰ to guide them, give them good health, etc.
Only Allah knows best
Written by Maulana Mohammad Ahsan Osmani Checked and approved by Mufti Mohammed Tosir Miah Darul Ifta Birmingham
 Tafseerul Qurtubi: v. 8, p. 249 (Maktabah Rasheedia)  Aysarul Tafaseer: p. 678 (Al-Maktabatul Asriya)