SB 11.18.21

vivikta-kṣema-śaraṇo
 mad-bhāva-vimalāśayaḥ
ātmānaṁ cintayed ekam
 abhedena mayā muniḥ
Synonyms: 
vivikta — solitary; kṣema — safe; śaraṇaḥ — his dwelling; mat — in Me; bhāva — by constant thought; vimala — purified; āśayaḥ — his consciousness; ātmānam — on the soul; cintayet — he should concentrate; ekam — alone; abhedena — not different; mayā — from Me; muniḥ — the sage.
Translation: 
Dwelling in a safe and solitary place, his mind purified by constant thought of Me, the sage should concentrate on the soul alone, realizing it to be nondifferent from Me.
Purport: 

One who is engaged exclusively in the devotional service of the Lord in one of the five principal relationships is to be known as a pure Vaiṣṇava. Because of his advanced stage of love of Godhead, a pure devotee is able to constantly chant the glories of the Lord without material hindrance. He is not interested in anything except Lord Kṛṣṇa and never considers himself to be qualitatively different from the Lord. One who is still attracted by the gross material body and subtle material mind, which cover the eternal soul, continues to see himself as different from the Supreme Personality of Godhead. This misconception is due to false identification with matter. With senses purified of material contamination, one must serve the Lord, who is the master of all senses, and thus one’s devotional service is considered free from discrepancy.

One who ignores the injunctions of Vedic literature uselessly wastes his sense activity in illusory material activities. He falsely considers himself to be different from Lord Kṛṣṇa and therefore imagines that he possesses an interest independent of the Lord’s interest. There is no possibility that such a person can achieve steadiness in life, because the material field of action is constantly being shifted and transformed by the disturbing influence of time. If a devotee begins to cultivate an interest apart from the loving service of the Lord, his meditation on his oneness with the Lord will be disturbed and overturned. When the mind deviates from the lotus feet of the Lord, the duality of material nature again becomes prominent within the mind, and one resumes a work program based on the three modes of material nature. One who is not fixed in one’s own relationship with the Supreme Lord cannot be fearless or steady and is deprived of the shelter of Lord Śrī Kṛṣṇa. Therefore one should seriously contemplate, as described in this verse, one’s identity as a small particle of consciousness not different from the supreme consciousness, Lord Kṛṣṇa. Thus one should remain steady in Kṛṣṇa consciousness.