What is the name of the Zoroastrian prayer beginning "Yatha ahu vairyo"?

The Zoroastrian prayer beginning “Yatha ahu vairyo” is called Ahuna Vairya.

Ahuna Vairya is also known by its opening words, Yatha Ahu Vairyo, and by the Middle Persian name Ahunwar or Ahunavar. It appears in Yasna 27.13, within the Avesta, the sacred textual tradition of Zoroastrianism. The prayer is written in an archaic form of Avestan and is regarded as one of the religion’s most sacred formulas.

The text is brief but notoriously difficult to translate. Its imagery concerns rightful authority, truth, good thought, and care for the poor, though translations differ because the original language is compressed and syntactically dense. Zoroastrian tradition also treats the prayer as a primordial utterance associated with Ahura Mazda and as a powerful spiritual protection.

Readers often confuse Ahuna Vairya with Ashem Vohu, another major Zoroastrian prayer. Both are short Old Avestan formulas and appear together near the beginning of the Gathic liturgical sequence, but they are distinct prayers. The Gathas themselves are a larger collection of seventeen hymns traditionally attributed to Zarathushtra.