The Avesta comprises the oldest extant sacred texts of Zoroastrianism. The scripture collection includes the Yasna; the Vispered, which covers festival observances; the Yashts, hymns of praise; the Vendidad, a book of ancient purity laws; and the Khordeh Avesta, or the “smaller Avesta” which contains the daily prayers. Within the Yasna are the Gathas, the oldest and most sacred teachings of the Avesta. The Gathas are the hymns of the Prophet Zarathushtra, which were orally transmitted by the Prophet’s followers for centuries.