Sahih Muslim Book 1, Hadith Number 415.

Chapter : Intercession of the Messenger of Allah (may peace be upon him) for Abu Talib and some remission for him on this account.

Nu’man b. Bashir reported: The Messenger of Allah (may peace be upon him) said: Verily the least suffering for the inhabitants of Fire would be for him who would have two shoes and two laces of Fire (on his feet), and with these would boil his brain as boils the cooking vessel, and he would think that he would not see anyone in a more grievous torment than him, whereas he would be in the least torment.