The holy book of Parsis is called Zend Avesta. It includes all the Parsis religious texts. The teachings and Principles of Prophet Zoroaster are a part of the book.
The book had a massive amount of manuscripts and scriptures that were said to be lost during Alexander’s period. It has five sections.
The main portion of the holy book consists of songs and hymns. It also has ‘Gathas’ written in Zoroaster’s words. The ‘Yasna’ part of the book contains sacrificial rituals and methods. A section of the book also gives tribute to the leaders of Zoroastrian.