Hazrat Abu Sa'id Khudri (may Allah be pleased with him) narrated that the Prophet Muhammad (peace and blessings be upon him) forbade drinking directly from the mouth of water-skins, that is, he prohibited opening the mouth of the water-skin and putting one's mouth to it to drink.
Hadith Referenceاللؤلؤ والمرجان / كتاب الأشربة / 1314
Hadith Gradingمحدثین:«صحیح»
Hadith Takhrij«صحیح، أخرجه البخاري في: 74 كتاب الأشربة: 23 باب اختناث الأسقية»
Brief Explanation
It is narrated in Musnad Abu Bakr ibn Abi Shaybah that a person drank water by placing his mouth directly on a water-skin (mashk). A small snake from the water-skin entered his stomach. For this reason, the Prophet sallallahu alayhi wa sallam strictly forbade this action. The narrations which indicate permissibility have been abrogated by this incident. (Fath al-Bari)