Sahih Muslim
The Book of Pilgrimage (Kitab Al-Hajj)
Book Number: 007 / Hadith Number: 3169
Abu Huraira (Allah be pleased with him) reported that Allah's Messenger (may peace be upon him) declared sacred the territory between two lava mountains of Medina. Abu Huraira said: If I were to find deer in the territory between the two mountains, I would not molest them, and he (the Holy Prophet) declared twelve miles of suburb around Medina as a prohibited pasture.