Narayana and Nara are supposed to have taken form as Sri Krishna and Arjuna. They were almost like twins, working together living together, eating together, one being in two bodies. The association of Sri Krishna with Arjuna, so inseparable, is an illustration of the inseparable relation between God and man.
यत्र योगेश्वर: कृष्णो यत्र पार्थो धनुर्धर: ।
तत्र श्रीर्विजयो भूतिर्ध्रुवा नीतिर्मतिर्मम ॥ ७८ ॥
yatra yogeśvaraḥ kṛṣṇo
yatra pārtho dhanur-dharaḥ
tatra śrīr vijayo bhūtir
dhruvā nītir matir mama
This truth is highlighted especially in the last verse of the Bhagavad Gita. “Yatra yogeshvarah Krishno, yatra partho dhanur dharah; Tatra srirvijayo bhutir dhruva nitir matir mama,” says Sanjaya.
“Where Sri Krishna, the Lord of Yog, is; and Arjuna, the wielder of the bow, is; simultaneously seated in one chariot, together; there perfection reigns supreme, success is at hand, all glory is there at once, and there is perfect righteousness.”
Divine grace and human effort go together. Knowledge and action are in the state of a perfect blend. The absolute and the relative are not two different entities; they are in one chariot.
The chariot in which Sri Krishna and Arjuna are seated may be the historical chariot that moved on the field of the Mahabharata, or it may be symbolic for Ishvara and Jiva, God and man who are working together in the human heart.
Or, this chariot can be the whole Universe, and it could be the Absolute enacting the drama of the relativity of manifestation.
The inseparability of Sri Krishna and Arjuna as friends, as has been told again and again in the Mahabharata, is an illustration of the point of the inseparability of God and man, the Creator and his Creation. It is to demonstrate this truth of the universality of God’s perfection and the ideal inclusiveness of everything that this incarnation shone on earth.