Yasna (Reverence). Third to Seventh Centuries AD:

Peterson, Joseph H, ed. ‘Yasna’ at Avesta – Yasna: Sacred Liturgy and Gathas/Hymns of Zarathushtra, 1995 (2010).
L H Mills, tr. from Sacred Books of the East, American Edition, 1898.
http://avesta.org/yasna/yasna.htm

Geldner, Karl F, ed. Avesta, the Sacred Books of the Parsis. Stuttgart: W Kohlhammer, 1896.
   http://avesta.org/yasna/yasna_transcription.pdf
   https://archive.org/download/in.ernet.dli.2015.217560/2015.217560.Avesta-The.pdf