SB 7.10.49
sa va ayam brahma mahad-vimrgya-
kaivalya-nirvana-sukhanubhutih
priyah suhrd vah khalu matuleya
atmarhaniyo vidhi-krd gurus ca
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
The impersonal Brahman is Krsna Himself because Krsna is the source of the impersonal Brahman. He is the origin of the transcendental bliss sought by great saintly persons, yet He, the Supreme Person, is your most dear friend and constant well-wisher and is intimately related to you as the son of your maternal uncle. Indeed, He is always like your body and soul. He is worshipable, yet He acts as your servant and sometimes as your spiritual master.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
There is always a difference of opinion about the Absolute Truth. One class of transcendentalists concludes that the Absolute Truth is impersonal, and another class concludes that the Absolute Truth is a person. In Bhagavad-gita, the Absolute Truth is accepted as the Supreme Person. Indeed, that Supreme Person Himself, Lord Krsna, instructs in Bhagavad-gita, brahmano hi pratisthaham, mattah parataram nanyat. “The impersonal Brahman is My partial manifestation, and there is no truth superior to Me.” That same Krsna, the Supreme Personality of Godhead, acted as the supreme friend and relative of the Pandavas, and sometimes He even acted as their servant by carrying a letter from the Pandavas to Dhrtarastra and Duryodhana. Because Krsna was the well-wisher of the Pandavas, He also acted as guru by becoming the spiritual master of Arjuna. Arjuna accepted Krsna as his spiritual master (sisyas te ’ham sadhi mam tvam prapannam), and Krsna sometimes chastised him. For example, the Lord said, asocyan anvasocas tvam prajña-vadams ca bhasase: “While speaking learned words, you are mourning for what is not worthy of grief.” The Lord also said, kutas tva kasmalam idam visame samupasthitam: “My dear Arjuna, how have these impurities come upon you?” Such was the intimate relationship between the Pandavas and Krsna. In the same way, a pure devotee of the Lord is always with Krsna through thick and thin; his way of life is Krsna. This is the statement of the authority Sri Narada Muni.