SB 11.11.49

athaitat paramaṁ guhyaṁ
 śṛṇvato yadu-nandana
su-gopyam api vakṣyāmi
 tvaṁ me bhṛtyaḥ suhṛt sakhā
Synonyms: 
atha — thus; etat — this; paramam — supreme; guhyam — secret; śṛṇvataḥ — to you who are listening; yadu-nandana — O beloved of the Yadu dynasty; su-gopyam — most confidential; api — even; vakṣyāmi — I will speak; tvam — you; me — of Me; bhṛtyaḥ — are the servant; su-hṛt — well-wisher; sakhā — and friend.
Translation: 
My dear Uddhava, O beloved of the Yadu dynasty, because you are My servant, well-wisher and friend, I shall now speak to you the most confidential knowledge. Please hear as I explain these great mysteries to you.
Purport: 

It is stated in the First Chapter of Śrīmad-Bhāgavatam (1.1.8), brūyuḥ snigdhasya śiṣyasya guravo guhyam apy uta: a bona fide spiritual master naturally reveals all transcendental secrets to a sincere disciple. Śrī Uddhava had completely surrendered to Lord Kṛṣṇa, and then only could the Lord explain such mysteries to him, because without complete faith the transmission of spiritual knowledge is impossible. Other processes of self realization, such as philosophical speculation, are imperfect and unsteady because the performer has personal desires, and there is no definite procedure by which to obtain the full mercy of the Supreme Lord. On the other hand, association with the pure devotees of the Lord is a self-sufficient process that is guaranteed to award the desired result. One must only learn how to associate with the pure devotees and one’s life will be perfect. That is the sum and substance of this chapter.

Thus end the purports of the humble servants of His Divine Grace A.C. Bhaktivedanta Swami Prabhupāda to the Eleventh Canto, Eleventh Chapter, of the Śrīmad-Bhāgavatam, entitled “The Symptoms of Conditioned and Liberated Living Entities.”