Hadith 114
It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both), he says that the Prophet Muhammad (peace and blessings be upon him) intended to perform ablution from a waterskin. It was said to him that this is (a waterskin) made from the hide of a dead (animal). The Prophet (peace and blessings be upon him) said: "Its tanning removes its impurity, filth, and uncleanness."