One should concentrate his mind upon the Supreme Personality of Godhead, who alone distributes Himself in so many manifestations just as ordinary persons create thousands of manifestations in dreams. One must concentrate the mind on Him, the only all-blissful Absolute Truth. Otherwise one will be misled and will cause his own degradation.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
स सर्वधीवृत्त्यनुभूतसर्व आत्मा यथा स्वप्नजनेक्षितैकः । तं सत्यमानन्दनिधिं भजेत नान्यत्र सज्जेद्यत आत्मपातः
sa sarvadhīvṛttyanubhūtasarva ātmā yathā svapnajanekṣitaikaḥ | taṃ satyamānandanidhiṃ bhajeta nānyatra sajjedyata ātmapātaḥ
SB 2.1.39