Hadith 764
Abu Sa'id Al-Khudri (May Allah be pleased with him) reported:
عن أبى سعيد الخدرى رضى الله عنه أن النبي صلى الله عليه وسلم نهى عن النفخ في الشراب، فقال رجل : القذاة أراها في الإناء؟ فقالب: "أهرقها" قال: إني لا أروى من نفس واحد؟ قال: "فأبن القدح إذاً عن فيك".((رواه الترمذي))
The Messenger of Allah (ﷺ) prohibited us blowing in the drinking water. A man said: "O Messenger of Allah! Sometimes I see some litter floating about on the surface. What should I do then?" He (ﷺ) replied, "Pour them out." Then the man said: "My thirst is not quenched with one draught." Messenger of Allah (ﷺ) said, "Then put away the cup from your mouth (in between three gulps), and take breath." [At-Tirmidhi].
In plain words
He forbade blowing into the drinking water. When asked about floating bits, he said to pour them out, and to lift the cup away and breathe between sips rather than gulp. Cleanliness made easy.
Reference : Riyad as-Salihin 764 In-book reference : Book 2, Hadith 38