On it being disliked to drink from the mouth of the vessel, and the clarification that the dislike is not a prohibition

Riyad as-Salihin (The Meadows of the Righteous)

by Imam Nawawi

112. Chapter: On it being disliked to drink from the mouth of the vessel, and the clarification that the dislike is not a prohibition

762. Abu Sa'id al-Khudri said, "The Messenger of Allah, may Allah bless him and grant him peace, forbade folding the mouths of waterskins inside out, i.e. folding back their mouths and drinking directly from them." [Agreed upon]

763. Abu Hurayra said, "The Messenger of Allah, may Allah bless him and grant him peace, forbade drinking from the mouth of a waterskin." [Agreed upon]

764. Umm Thabit Kabsha bint Thabit, the sister of Hassan ibn Thabit said, "The Messenger of Allah, may Allah bless him and grant him peace, visited us and drank from the mouth of a hanging water-skin. I went to its mouth and cut it off." [at-Tirmidhi]

She cut it off in order to preserve the place which the mouth of the Messenger of Allah, may Allah bless him and grant him peace, had touched and to seek its blessing and to protect it from being soiled. This hadith can be applied to make the permission clear. The first two hadiths clarify the best and most perfect way to act, and Allah knows best.