Wáj or Báj, is an “Avestan formula of benediction,” which serves to invoke Gods/Immortals favor upon life activities via sacred speech. Wáj/Báj must be recited in the words of the Avestan language that exude great power.
The term wáj is derived from Old Iranian wăk, Avestan vač “voice, word, language, speech.” Wáj goes back to Indo-European *Wékwos “word, speech.” Old Norse vátta “voice, word,” Greek épos “epic poem” are cognates.
Ancient Zoroastrians, and Indo-Europeans in general, believed that “words” have their unique magical power, and that “sacred words/speech” are the blueprint of the creation of the worlds. In Old Norse we read of songsmith, and spellsmith “poet.” In the poetic Gathas/Songs, the lordly ahuras, forge/fashion the poetic thought (mánthra.)
Wáj formulae consecrates the earthly acts with sacred spiritual power, and must be recited gracefully. Once the initial portion of the wáj preceding the action has been recited, quiet has to be maintained till the wáj is concluded by the recitation of the concluding portion. For example after the initial wáj for breaking bread (eating,) or wáj for bathing is recited no other words may be pronounced, complete silence must maintained until the concluding wáj formulae is spoken after the meal and/or bathing. If any other communication becomes necessary during the silent period, it must be done so inarticulately, and not via spoken word.
During Zoroastrian sacred rituals, Priests take wáj between themselves in order to make more effective the rite about to be performed, and maintain the full magic of the ritual.
The term wāj is also used for invocation formulae at the beginning and the end of long Avestan prayers. The term Wāj Yašt Srösh is a beautiful prayer dedicated to Sraôša, the Lord of Sacred Speech and Inspiration.”