The Upanishads - Mandhata Global

That sacrifice is inclined to the north in which there is a
Brahma priest who knows this. And with regard to such
a Brahma priest, there is the following gatha: "Wherever
it is injured, thither he (the Brahma priest) goes." The
silent Brahma alone, as one or the priests, protects the
sacrificer, as a mare protects a warrior. Because the
Brahma priest who knows this protects the sacrifice, the
sacrificer and all the priests, one should therefore make
a person who knows this the Brahma priest and not one
who knows it not, yea, not one who knows it not.
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