"Shayest Na-Shayest (Proper and Improper) is a compilation of miscellaneous laws and customs regarding sin and impurity, and other memoranda about ceremonies and religious subjects in general." It quotes many times from Avesta texts which are no longer extant.
Chapter 1. The names and amounts of the various degrees of sin; the names of the chief commentators on the Vendidad
Chapter 2. Precautions to be taken regarding corpses and menstruous women, the pollution caused by a serpent
Chapter 3. More precautions
Chapter 4. The proper size and materials of the sacred thread-girdle [kusti] and shirt, giving some details about the sins of running about uncovered and walking with one boot
Chapter 5. The sin of unseasonable chatter
Chapter 6. Details about good works, and those who can and cannot perform them; in which reference is made to Christians, Jews, and those of other persuasions
Chapter 7. Reverencing the sun and fire; the sin of extinguishing fire
Chapter 8. Confession and renunciation of sin, atonement for sins, especially mortal sins, both those affecting others and those only affecting one's own soul; a digression (Chap. 8.3) prohibiting the rich from hunting.
Chapter 9. The Hasar of time; priests passing away in idolatry; the discussion of religion; ceremonies not done aright; throwing a corpse into the sea; evil of eating in the dark; the four kinds of worship; when the angels should be invoked in worship; the ephemeral nature of life
Chapter 10. proper looseness for a kusti (sacred thread-girdle); when the sacred cake [dron] set aside for the guardian spirits [farohars] can be used; maintaining a fire where a woman is pregnant; providing a tank for ablutions; the Gathas not to be recited over the dead; food and drink not to be thrown away to the north at night; unlawful slaughter of animals; how the corpse of a pregnant woman should be carried; forgiveness of trespasses; evil of walking without boots; when the sacred girdle is to be assumed; breaking the spell of an inward prayer; ten women wanted at childbirth, and how the infant is to be treated; sin of beating an innocent person; evil of a false judge; men and women who do not marry; a toothpick must be free from bark; acknowledging the children of a handmaid; advantage of offspring and of excess in almsgiving; prayer on lying down and getting up; Avesta not to be mumbled; doubtful actions to be avoided or consulted about; evil of laughing during prayer; crowing of a hen; treatment of a hedgehog; after a violent death corruption does not set in immediately; necessity of a dog's gaze; putrid meat and hairy calces or butter unfit for ceremonies; when a woman can do priestly duty
Part 2. A Supplementary Treatise.
Chapter 11. The names and amounts of the various degrees of sin (again); the proper meat-offerings for various angels [yazads] and guardian spirits [farohars].
Chapter 12. The simplest form of worship; necessity of submitting to a high-priest; advantage of a fire in the house; sin of clothing the dead; presentation of holy-water to the nearest fire after a death; nail-parings to be prayed over; advantage of light at childbirth; offerings to the angels; maintaining a fire where a woman is pregnant and a child is born; a toothpick must be free from bark; acknowledging the children of a handmaid; advantage of offspring and of excess in almsgiving; evil of drawing well-water at night; food not to be thrown away to the north at night; advantage of prayer at feasts; treatment of a hedgehog; praying when washing the face; the proper choice of a purifying priest; no one should be hopeless of heaven; necessity of a wife being religious as well as her husband; the ceremonies which are good works; the cause of sneezing, yawning, and sighing.
Chapter 13. An account of the mystic signification of the Gathas
Chapter 14. The errors which may be committed in consecrating the sacred cakes [dron], and how the beginning of the morning watch is to be determined.
Part 3 Appendix
Chapter 15. The intangible nature of Ohrmazd and the archangels; an account of how each of the archangels can be best propitiated, by a proper regard for the particular worldly existence which he specially protects
Chapter 16. The various degrees of sin, and of the amount of good works attributed to various ceremonies
Chapter 17. An account of the ceremonies after a death; particulars of those who have no part in the resurrection; the duty of submission to the priesthood; whether evil may be done for the sake of good; the place where people will rise from the dead
Chapter 18. Aeshm's complaint to Ahriman of the three things he could not injure in the world
Chapter 19. The occasions on which the Ahunwar formula should be recited, and the number of recitals that are requisite, etc.
Chapter 20. Admonition to frequent the fire temple; nature of wisdom; admonitions to avoid nasu, to use gomez, to observe Kwarshed Niyayesh, and to destroy noxious creatures; three greatest concerns; three places to frequent; acts benefiting the soul or body; Gathas and patets; anxiety; truth and deceit; extinguishing fire; gifts to the vile; on what to fix the attention; Fredun and Azi Zohak
Chapter 21. The lengths of midday and afternoon shadows (for calculating the beginning of Uzerin)
Chapter 22. Blessings invoked from the thirty angels and archangels who preside over the days of the month
Chapter 23. Special epithets of the same