1؎: The reason for the prohibition is evident: in this situation, the water is not visible, and there is a risk that there may be filth or an insect in the water, and one might drink it. Secondly, there is the consideration that the water skin (mashk) may develop an unpleasant odor. Thirdly, there is the risk of the water spilling. And according to most scholars, this prohibition is of a discouraging (tanzihi) nature, meaning it is contrary to what is preferable (khilaf awla).
Narrated Abu Huraira: Allah's Apostle forbade drinking directly from the mouth of a water skin or other leather containers. and forbade preventing one's neighbor from fixing a peg in (the wall of) one's house.
Maulana Dawood Raz
Hadith Commentary:
What has happened to the Muslims in our times that, even over such trivial matters, they quarrel and fight to the extent of taking the issue to court, thereby ruining both their worldly life and their religion?
Source: Sahih Bukhari: Commentary by Maulana Dawood Raz, Page: 5627