From the beginning of creation, the three words oḿ tat sat were used to indicate the Supreme Absolute Truth. These three symbolic representations were used by brāhmaṇas while chanting the hymns of the Vedas and during sacrifices for the satisfaction of the Supreme.
indication of the Supreme
that
eternal
thus
indication
of the Supreme
threefold
is considered
the brahmanas
with that
the Vedic literature
also
sacrifice
also
used
formerly.