Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) says that the Messenger of Allah (peace and blessings be upon him) forbade drinking from the mouth of a waterskin, forbade riding an animal that eats filth, and (forbade) the mujaththamah, a goat that is pelted with stones until it is killed.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 10331