Sacred Books and Traditions of the Yezidiz, by Isya Joseph, [1919], at sacred-texts.com
They are divided into seven classes; and each class has functions peculiar to itself that cannot be discharged by any of the other classes. They are:
1. Šeiḫ. He is the servant of the tomb, and a descendant of Imam, Ḥasan al-Baṣrî. No one can give a legal decision or sign any document except the šeiḫ who is the servant of Šeiḫ ‘Adî's tomb. He has a sign by which he is distinguished from others. The sign is a belt which he puts on his body, and net-like gloves, which resemble the halters of camels. If he goes among his people, they bow down and pay him their respects. The šeiḫs sell a place in paradise to anyone who wishes to pay money.
2. Emir. The emirship specifically belongs to the descendants of Yezîd. They have a genealogical tree, preserved from their fathers and forefathers, which goes up to Yezîd himself. The emirs have charge of .the temporal and governmental affairs, and have the right to say, "Do this and do not that,"
3. Ḳawwâl. He has charge of tambourines and flutes and religious hymns.
4. Pîr. To him appertain the conduct of fasts, the breaking of fasts, and hair-dressing.
5. Kôchak. To him appertain the duties of religious
instruction, and sepulture, and interpretation of dreams, i.e., prophecy.
6. Faḳîr. To him appertain the duties of instruction of boys and girls in playing on the tambourines, in dancing and religious pleasure. He serves Šeiḫ ‘Adî.
7. Mulla. To him appertain the duties of instructing children. He guards the books and the mysteries of religion and attends to the affairs of the sect.