as distinguished from ghasl (washing) is the religious act of bathing the whole body after a legal impurity. It is founded upon the express injunction of the Qur’an, Surah v 9: “If ye are polluted then purify yourselves.” And the traditions most minutely relate the occasions on which the Prophet performed the ceremony of ghusl, or bathing. The Muslim teachers of all sect are unanimous in prescribing the washing of the whole body after the following acts, which render the body junub, or impure: (1) Hayz menses; (2) nifas, puerperium; (3) jimi’, coitus; (4) ihtilam pollution nocturna. It is absolutely necessary that every part of the body should be washed, for ‘Ali relates that the Prophet said “He who leaves but one hair unwashed on his body will be punished in hell accordingly.” (Mishkat, book ii c viii).
Based on Hughes, Dictionary of Islam