Bhagavad Gita, Chapter 17, Verse 23

ॐतत्सदिति निर्देशो ब्रह्मणस्त्रिविधः स्मृतः । ब्राह्मणास्तेन वेदाश्च यज्ञाश्च विहिताः पुरा

oṃtatsaditi nirdeśo brahmaṇastrividhaḥ smṛtaḥ | brāhmaṇāstena vedāśca yajñāśca vihitāḥ purā

Translation

"Oṃ, Tat, Sat": this has been taught to be the triple designation of Brahman. By that were created of old the brāhmaṇas and the Vedas and the sacrifices.

— Alladi Mahadeva Sastri

Word meanings

oṃ

Aum

tat

That

sat

Being

iti

thus

nirdeśaḥ

designation

brahmaṇaḥ

of Brahman

trividhaḥ

threefold

smṛtaḥ

remembered

brāhmaṇāḥ

Brāhmaṇas

tena

by this

vedāḥ

Vedas

ca

and

yajñāḥ

sacrifices

ca

and

vihitāḥ

ordained

purā

formerly

Śaṅkarācārya's commentary

"Taught": in the Vedānta by the knowers of Brahman. "By that, etc.": by the triple designation. This is said in praise of the triple designation.