رِيَاضُ الصَّالِحِينَ
Riyad as-Salihin 761
The Book About the Etiquette of Eating
Undesirability of Drinking Directly from the Mouth of a Water-Skin
عَنْ أبى سَعِيدٍ الخدرى رضى اللَّه عَنْهُ قَالَ : نَهَى رَسُولُ اللَّهِ عَنِ اخْتِنَاثِ الأَسْقِيَةِ : يعنى: أَنْ تُكْسَرَ أَفْوَاهُهَا، ويشرب منها.((مُتَّفَقٌ عَلَيْهِ))
Abu Sa'id Al-Khudri (May Allah be pleased with him) reported: The Messenger of Allah (ﷺ) forbade turning the water-skin upside down and drinking directly from its mouth. [Al-Bukhari and Muslim].
Riyad as-Salihin, 761