Sanskrit
ऋषिभिर्बहुधा गीतं छन्दोभिर्विविधैः पृथक् । ब्रह्मसूत्रपदैश्चैव हेतुमद्भिर्विनिश्चितैः ॥
ṛṣibhir bahudhā gītaṃ chandobhir vividhaiḥ pṛthak brahmasūtrapadaiś caiva hetumadbhir viniścitaiḥ
Translation
Rishis have sung in manifold ways, in many various chants, and in decisive Brahma-sûtra verses full of reasonings.
Annie Besant · The Bhagavad-Gita, translated by Annie Besant (4th ed., 1922) — Wikisource · Public Domain
Explanation
Krishna grounds what follows in prior authority — rishis (seers), Vedic chants, and the terse aphoristic “Brahma-sutra” verses — before he’s said a word of the actual content. It’s a rhetorical move he uses elsewhere too, invoking prior sages rather than claiming pure originality, and it signals that the kshetra/kshetrajna framework about to be laid out is being presented as received wisdom, consistent with the Samkhya-style enumeration that follows in verses 6-7.