Bhagavad-gītā 4.3
BG 4.3
Open the full passageस एवायं मया तेऽद्य योगः प्रोक्तः पुरातनः । भक्तोऽसि मे सखा चेति रहस्यं ह्येतदुत्तमम् ॥३॥
Sanskrit
sa evāyaṁ mayā te 'dya yogaḥ proktaḥ purātanaḥ bhakto 'si me sakhā ceti 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.