Shaykh al-Islām—may Allah sanctify his soul—said:
Someone asked: “In what language will people be addressed on the Day of Resurrection? Will Allah Most High address them in Arabic? Is it true that the language of the people of Hell is Persian and that the language of the people of Paradise is Arabic?”
After saying, “Praise be to Allah, Lord of all worlds,” I answered him:
It is not known what language people will speak that day, nor in what language they will hear the address of the Lord, Glorious and Exalted. Neither Allah Most High nor His Messenger—peace and blessings be upon him—has informed us of any of this. It has not been authentically established that Persian is the language of the people of Hell, or that Arabic is the language of those enjoying eternal bliss. We know of no disagreement concerning this among the Companions—may Allah be pleased with them. Rather, they all refrained from discussing it, because speaking about such matters is superfluous talk; nor did Allah Most High say anything concerning this to the people of the earth. However, disagreement on this matter arose among later generations.
Some said: “They will converse in Arabic.” Others said: “Except for the people of Hell: they will reply in Persian, which is their language in Hell.”