Rites necessary for Hebrew men and women in the frequent events of their contracting a kind of ritual impurity, as in menstruation or by touching a corpse. It was the duty of a priest to remove the traces of impurity by means of a sacrifice at an altar (Lev. 14: 25). The subject is mentioned by John 2: 6, where it is explained for Gentile readers. At John 3: 25 there is a difficulty about the precise Greek reading, and the discussion between John the Baptist's disciples and a Jew over a purification has been thought by some scholars to indicate that the Baptist's disciples sided with other Jews against Jesus in requiring strict adherence to the purificatory laws.