Bhagavad Gita Chapter 13, Verse 5

ऋषिभिर्बहुधा गीतं छन्दोभिर्विविधैः पृथक् | ब्रह्मसूत्रपदैश्चैव हेतुमद्भिर्विनिश्चितैः ||

ṛṣibhir bahudhā gītaṁ chandobhir vividhaiḥ pṛthak brahma-sūtra-padaiś caiva hetumadbhir viniścitaiḥ

This has been sung by sages in various ways, in different verses, and also in the words of the Brahma Sutras, which are full of reasoning and are definitely established.

Krishna acknowledges that the description of the field has been given by sages in many ways—through various verses, philosophical texts, and the Brahma Sutras. This establishes the teaching's authority and tradition. But he's about to give a clear, direct explanation. Most people encounter this knowledge through different sources—philosophy, religion, science, psychology. But the core teaching remains the same: understanding the distinction between field and knower. The form may vary, but the essence is constant. Krishna will now present it in the clearest way possible.