Bhagavad Gita 18.64
Listen to My last word once more, the deepest secret of all; you are My beloved, you are My friend, and I speak for your welfare.
सर्वगुह्यतमं भूयः श्रृणु मे परमं वचः।इष्टोऽसि मे दृढमिति ततो वक्ष्यामि ते हितम्॥sarvaguhyatamaṃ bhūyaḥ śrṛṇu me paramaṃ vacaḥ|iṣṭo'si me dṛḍhamiti tato vakṣyāmi te hitam||
English translation (above): Shri Purohit Swami (1935), public domain. Sanskrit text via github.com/gita/gita (Unlicense).