Bhagavad Gita 4.3

It is the same ancient path that I have now revealed to you, for you are my devotee and my friend. It is the supreme secret.

स एवायं मया तेऽद्य योगः प्रोक्तः पुरातनः।
भक्तोऽसि मे सखा चेति रहस्यं ह्येतदुत्तमम्॥

sa evāyaṃ mayā te'dya yogaḥ proktaḥ purātanaḥ|
bhakto'si me sakhā ceti rahasyaṃ hyetaduttamam||

English translation (above): Shri Purohit Swami (1935), public domain. Sanskrit text via github.com/gita/gita (Unlicense).