Other parts of Avesta are named Yasna , Yashts , Visperad , Vendidad and Khordeh Avesta . Taken together , the Khordeh Avesta is considered the prayer book for general lay use . In a wider sense , the term Khordeh Avesta includes all material other than the Yasna , the Visparad and the Vendidad , as it is only the ceremonies contained in these three books that are reserved for the priests .