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.[At- Tirmidhi].
App reference: Book 3, Hadith 37
Arabic/English book reference: Book 3, Hadith 764