It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "In Hell, the distance between the two shoulders of the disbeliever will be equal to three days' journey for a fast rider."
Hadith Referenceالمعجم الأوسط / باب الباء / 3270
Hadith Takhrij«أخرجه البخاري فى «صحيحه» برقم: 6551، ومسلم فى «صحيحه» برقم: 2852»