عن أبي هريرة وعبد الله بن عباس رضي الله عنهم قالا: نَهَى رسولُ اللهِ صلى الله عليه وسلم أَنْ يُشْرَبَ مِنْ فِي السِّقاءِ أو القِرْبَةِ.
Abu Hurayrah and Ibn ‘Abbās (may Allah be pleased with him) reported: The Messenger of Allah (may Allah's peace and blessings be upon him) prohibited drinking directly from the mouth of a waterskin.
The Messenger of Allah (may Allah's peace and blessings be upon him) prohibited drinking directly from the mouth of a waterskin because of the fear of harm. There could be something in it that the one drinking can not see, and it might get into his stomach.