Bhagavad Gita, Chapter 13, Verse 5

This truth has been sung by Rishis in many ways, in various distinctive chants, in passages indicative of Brahman, full of reasoning, and convincing.

This teaching is grounded here in a real, existing body of work, not offered as one person's private insight.

Naming sages, hymns, and the Brahma Sūtra ties this teaching to something already established and reasoned through. Real authority is shown resting on accumulated evidence, not asserted alone.