Sunan Ibn Majah, Chapter: The Chapters of Purification and its Sunnah

that his father said: "I heard the Messenger of Allah (saw) being asked about water in the wilderness that is frequented by beasts and predators. The Messenger of Allah (saw) said: "If the water reaches the amount of two Qullah,* nothing can make it impure (Najis).'" (Sahih) Another chain with similar wording. *A Qullah is a large water container whose size the scholars differ over, from five to fifty waterskins. Tirmidhi said (no. 67): "And they say, it is approximately fifty Qirbah (water skins)." Khattabi said (Maalamus-Sunan: 1:35): "The scholars have stated that the size of two Qullah is five Qirbah." See Ahmad Shakir's comments on Jami At-Tirmidhi.