''Shāyast ne-Shāyast'' (
MP: "Proper and Improper") is an 8th/9th-century
Zoroastrian
Zoroastrianism is an Iranian religion and one of the world's oldest organized faiths, based on the teachings of the Iranian-speaking prophet Zoroaster. It has a dualistic cosmology of good and evil within the framework of a monotheistic ont ...
Middle Persian
Middle Persian or Pahlavi, also known by its endonym Pārsīk or Pārsīg () in its later form, is a Western Middle Iranian language which became the literary language of the Sasanian Empire. For some time after the Sasanian collapse, Middle Pe ...
compilation of miscellaneous laws and customs regarding sin and impurity, with other memoranda about ceremonies and religious subjects in general. The text contains about 13,500 words.
The content of this collection are of a very varied character, but sins and good works, precautions to avoid impurities, details of ceremonies and customs, the
mystic signification of the