Imam Ishaq bin Rahwayh (may Allah have mercy on him) narrates: I said to Abu Usamah: "Did Abu Rawq, whose name is Atiyyah bin al-Harith, narrate to you that Salih bin Abi Tarif (may Allah have mercy on him) narrated to him, saying: I asked Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him): Did you hear the Messenger of Allah (peace and blessings be upon him) say anything about this verse: "Perhaps those who disbelieve will wish that they had been Muslims"? He said: Yes, I heard him (peace and blessings be upon him) say: "Allah Almighty will bring some people of the believers out of the Fire, after He has taken His retribution from them." And he said: "When Allah Almighty admits them into the Fire along with the polytheists, the polytheists will say to them: You used to claim in the world that you were the friends of Allah, so what is the matter with you that you are with us in the Fire? When Allah Almighty hears this from them, He will grant permission for intercession for them. So the angels and the prophets will intercede, and the believers will intercede, until they come out by the permission of Allah. When the polytheists see this, they will say: If only we had been like them, so that intercession would reach us too and we would come out with them." He (peace and blessings be upon him) said: "That is the meaning of the saying of Allah: "Perhaps those who disbelieve will wish that they had been Muslims." Then in Paradise they will be called 'al-Jahannamiyyun' (the people of Hell) because of black marks on their faces, and they will say: O our Lord! Remove this name from us. So Allah Almighty will command them, and they will bathe in the river of Paradise, and that name will be removed from them." Abu Usamah affirmed it and said: "Yes."
Hadith Referenceالمعجم الأوسط / باب الميم / 8110
Hadith Takhrij«أخرجه ابن حبان فى «صحيحه» برقم: 7432»