It was narrated from 'Ubaidullah bin 'Abdullah bin 'Umar that his father said:"I heard the Messenger of Allah being asked about water in the wilderness that is frequented by beasts and predators. The Messenger of Allah said: "If the water reaches the amount of two Qullah, nothing can make it impure (Najis).'" (Sahih) Another chain with similar wording

English translation · Sunan Ibn Majah