C.C. Adi 1.61

īśvara-svarūpa bhakta tāńra adhiṣṭhāna

bhaktera hṛdaye kṛṣṇera satata viśrāma

A pure devotee constantly engaged in the loving service of the Lord is identical with the Lord, who is always seated in his heart.

The Supreme Personality of Godhead is one without a second, and therefore He is all-powerful. He has inconceivable energies, of which three are principal. The devotee is considered to be one of these energies, never the energetic. The energetic is always the Supreme Lord. The energies are related to Him for the purpose of eternal service. A living entity in the conditioned stage can uncover his aptitude for serving the Absolute Truth by the grace of Kṛṣṇa and the spiritual master. Then the Lord reveals Himself within his heart, and he can know that Kṛṣṇa is seated in the heart of every pure devotee. Kṛṣṇa is actually situated in the heart of every living entity, but only a devotee can realize this fact.