4.3
स एवायं मया तेऽद्य योगः प्रोक्तः पुरातनः | भक्तोऽसि मे सखा चेति रहस्यं ह्येतदुत्तमम् ||३||
sa evāyaṁ mayā te'dya yogaḥ proktaḥ purātanaḥ bhakto'si me sakhā cheti rahasyaṁ hy etad uttamam
Translation
That very ancient science of the relationship with the Supreme is today told by Me to you because you are My devotee as well as My friend and can therefore understand the transcendental mystery of this science.
Interpretation
Why is Krishna telling this to Arjuna specifically? Because Arjuna is both a devotee (bhakta) and a friend (sakhā). The supreme mystery ('uttamam rahasyam') can only be received by one who has the heart capable of receiving it — not mere intellectual curiosity, but loving openness and trust.