Riyad as-Saliheen 764
Umm Thabit Kabshah (May Allah be pleased with her), daughter of Thabit (May Allah be pleased with him) and the sister of Hassan bin Thabit, the Prophet's poet) reported:
Messenger of Allah ﷺ visited me and drank some water from a hanging water-skin while he was in a standing posture. So, I stood up and cut off the mouth (of that water-skin). An-Nawawi said that the reason why she did this was to keep to receive benediction that part of the water-skin which the lips of Messenger of Allah ﷺ touched.
وعن أم ثابت كبشة بنت ثابت أخت حسان بن ثابت رضى الله عنه وعنها قالت: دخل على رسول الله ﷺ، فشرب من في قربة معلقة قائماً، فقمت إلى فيها فقطعته. .