Sahih Muslim
The Book Pertaining to Paradise, Its Description, Its Bounties and Its Intimates (Kitab Al-Jannat wa Sifat Naimiha wa Ahliha)
Book Number: 040 / Hadith Number: 6832
Abu Huraira reported directly from Allah's Messenger (may peace be upon him) that he said: The distance of the two shoulders of the non-believer in Hell will be a three-day journey for a swift rider.