GUARDIAN SPIRITS
We worship the good, strong, beneficent Fravashis [guardian spirits] of the faithful; with helms of brass, with weapons (45) of brass, with armor of brass; who struggle in the fights for victory in garments of light, arraying the battles and bringing them forwards, to kill thousands of Dævas [demons]. 46. When the wind blows from behind them and brings their breath unto men, then men know where blows the breath of victory: and they pay pious homage unto the good, strong, beneficent Fravashis of the faithful, with their hearts prepared and their arms uplifted. 47. Whichever side they have been first worshiped in the fulness of faith of a devoted heart, to that side turn the awful Fravashis of the faithful along with Mithra [angel of truth and light] and Rashnu [Justice] and the awful cursing thought of the wise and the victorious wind.
Yasht xiii. 45-47: Translation of J. Darmesteter.