The Prophet ﷺ forbade drinking directly from the mouth of a waterskin.
نهى النبي ﷺ عن الشرب من في السقاء.
No references are available.
Bukhari narrated it in the Book of Drinks (5629) from Musaddad, who said, Yazid bin Zuray narrated to us, who said, Khalid narrated to us, from Ikrima, from Ibn Abbas, who related it.