<Tr> <Td> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> </Td> </Tr> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> <P> The Avesta / əˈvɛstə / is the primary collection of religious texts of Zoroastrianism, composed in the otherwise unrecorded Avestan language . Collected during the Sassanid Period of much more ancient oral accounts, according to Jean Kellens, "The book was originally given the name abestag, which the Parsees later turned into Avesta and which probably comes from the Old Iranian upa - stavaka,' praise (of Ahura Mazda)' .". </P> <P> The Avesta texts fall into several different categories, arranged either by dialect, or by usage . The principal text in the liturgical group is the Yasna, which takes its name from the Yasna ceremony, Zoroastrianism's primary act of worship, and at which the Yasna text is recited . The most important portion of the Yasna texts are the five Gathas, consisting of seventeen hymns attributed to Zoroaster himself . These hymns, together with five other short Old Avestan texts that are also part of the Yasna, are in the Old (or' Gathic') Avestan language . The remainder of the Yasna's texts are in Younger Avestan, which is not only from a later stage of the language, but also from a different geographic region . </P>

Of which religion is the avesta a sacred book