B.G 4.01, 02, and 03
श्रीभगवानुवाच
इमं विवस्वते योगं प्रोक्तवानहमव्ययम्। विवस्वान्मनवे प्राह मनुरिक्ष्वाकवेब्रवीत् ॥१॥
Sri Bhagavān said:
I shared this eternal and undying Yōga with the Sun. He taught it to his son Manu, and Manu narrated it to Iksvaku.
एवं परम्पराप्राप्तमिमं राजर्षयो विदुः। स कालेनेह महता योगो नष्टः परन्तप ॥२॥
Thus, the knowledge was passed down through the disciple succession of royal kings. But, O Scorcher of foes, as time passed, this magnificent Yōga was lost.
स एवायं मया तेऽद्य योगः प्रोक्तः पुरातनः। भक्तोऽसि मे सखा चेति रहस्यं ह्येतदुत्तमम् ॥३॥
Because you are both my dear friend and a devoted student, I have shared that same secret supreme knowledge, the ancient Yōga, to you.
Gīta Bhāshya 4.01-03
This chapter delves into the immense significance of the Supreme, the process of distinguishing actions, and the crucial role of knowledge. This verse provides evidence that the knowledge to be shared was prevalent in the past as well.
बुद्धेः परस्य माहात्म्यं, कर्मभेदः, ज्ञानमाहात्म्यं च उच्यते अस्मिन्नध्याये।
Understanding of the greatness of Supreme, how to differentiate the duties, and the greatness of knowledge are narrated in this chapter.
पूर्वानुष्ठितश्चायं धर्मः इत्याह - इमम् इति ॥१-३॥
Previously also DHARMA was practiced is indicated by 'imam' verse.
Gīta Tātparya 4.01-03
This chapter explores the concepts of knowledge and the nature of actions in great detail. The Bhagavad Gita is a part of the Pancharatra tradition.
उक्तयोः ज्ञानकर्मणोरुभयोः विशेषविस्तरात्मकोऽयमध्यायः।
The topics of knowledge and duties are dealt with special depth in this chapter.
"ब्रह्मरुद्रेन्द्र सूर्याणां यद्दत्तं विष्णुना पुरा। पञ्चरात्रात्मकं ज्ञानं व्यासोऽदात् पाण्डवेषु तत्। तेषामेवावतारेषु सेनामध्येऽर्जुनाय च। प्रादात् गीतेति निर्दिष्टं सङ्क्षेपेणायुयुत्सवे॥
The knowledge of Pancharatra that was given to Brahma, Rudra, Indra and the Sun previously by lord Vishnu, that same knowledge was imparted to Pandavas in their incarnations by Vyasa. Vyasa presented it to Arjuna in the middle of the armies, as Bhagavad Gita, that is definitive and concise.
यथा कुर्वन्ति कर्माणि यथा जानन्ति देवताः। सर्वे कार्तयुगाश्चैव नृपाश्च मनुपूर्वकाः। ज्ञातव्यं चैव कर्तव्यं यथा सर्वैः मुमुक्षुभिः। त्रैतादित्रिषु जातैश्च गीतायां तदुदाहृतम्॥
The way a person performs deeds, gods known him to be that. All kings have performed deeds in accordance with Manu, since Krita age. All seekers of liberation should know and practice these deeds. Thus, the Bhagavad Gita elaborates on the three Vedas and their origin.
पाण्डवाद्याः क्षेमकान्ताः करिष्यन्ति च जानते। तथैव तेन गीताया नास्ति शास्त्रं समं क्वचित्। वेदार्थपूर्वकं ज्ञेयं पञ्चरात्रं यतोऽखिलम्। तत्सङ्क्षेपश्च गीतेयं तस्मान्नास्याः समं क्वचित्॥"
Stating from Pandavas to king Kshema understood and acted accordingly. Therefore, it is said, there is no scripture equal to the Bhagavad Gita anywhere. Study and practice of the Pāñcarātra gives the knowledge of the Vedas. The Bhagavad Gita provides the summary and essence of Pāñcarātra. Therefore, there is no scripture equal to it anywhere.
इति ब्रह्मवैवर्ते ॥१-३॥
-states Brahma Vaivarta Purana.