The Supreme Personality of Godhead, Vāsudeva, Kṛṣṇa, is extremely difficult to understand for unintelligent men who accept Him as impersonal or void, which He is not. The Lord is therefore understood and sung about by pure devotees.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
यत्तद्ब्रह्म परं सूक्ष्ममशून्यं शून्यकल्पितम् । भगवान् वासुदेवेति यं गृणन्ति हि सात्वताः
yattadbrahma paraṃ sūkṣmamaśūnyaṃ śūnyakalpitam | bhagavān vāsudeveti yaṃ gṛṇanti hi sātvatāḥ
SB 9.9.49