Sahih al-Bukhari Book 74, Hadith 51
Allah's Messenger (ﷺ) forbade the bending of the mouths of water skins for the sake of drinking from them.
Allah's Messenger (ﷺ) said, "Extinguish the lamps when you go to bed; close your doors; tie the mouths of your water skins, and cover the food and drinks." I think he added, ". . . even with a stick you place across the container."
I heard Allah's Messenger (ﷺ) forbidding the drinking of water by bending the mouths of water skins, i.e., drinking from the mouths directly.