What is the evidence for the purity of human hair after it has been cut or plucked?

The madhhab of the majority of scholars is that human hair is pure without qualification. They have adduced as proof the hadith of Anas, may Allah be pleased with him, that the Prophet, peace and blessings be upon him, distributed his hair among his companions after shaving it during the Farewell Pilgrimage. Had it been impure, that would not have been permissible.