Mukhtasar Bukhari (Abridged) 1943 — Drinking from a water skin

Narrated Abu Sa'id Al-Khudri (may Allah be pleased with him): The Messenger of Allah (peace and blessings of Allah be upon him) forbade turning the water-skin upside down (i.e., the Messenger of Allah, peace be upon him, forbade drinking water from the mouth of the water-skin by turning it over).