SB 4.22.9

naiva lakṣayate loko
 lokān paryaṭato ’pi yān
yathā sarva-dṛśaṁ sarva
 ātmānaṁ ye ’sya hetavaḥ
Synonyms: 
na — not; eva — thus; lakṣayate — can see; lokaḥ — people; lokān — all planets; paryaṭataḥ — traveling; api — although; yān — whom; yathā — as much as; sarva-dṛśam — the Supersoul; sarve — in all; ātmānam — within everyone; ye — those; asya — of the cosmic manifestation; hetavaḥ — causes.
Translation: 
Pṛthu Mahārāja continued: Although you are traveling in all planetary systems, people cannot know you, just as they cannot know the Supersoul, although He is within everyone’s heart as the witness of everything. Even Lord Brahmā and Lord Śiva cannot understand the Supersoul.
Purport: 

In the beginning of the Śrīmad-Bhāgavatam it is said, muhyanti yat sūrayaḥ. Great demigods like Lord Brahmā, Lord Śiva, Indra and Candra are sometimes bewildered trying to understand the Supreme Personality of Godhead. It so happened that when Kṛṣṇa was present on this planet, Lord Brahmā and King Indra also mistook Him. And what to speak of great yogīs or jñānīs who conclude that the Absolute Truth, the Personality of Godhead, is impersonal? In the same way, great personalities and Vaiṣṇavas like the four Kumāras are also invisible to ordinary persons, although they are traveling all over the universe in different planetary systems. When Sanātana Gosvāmī went to see Lord Śrī Caitanya Mahāprabhu, he could not be recognized by Candraśekhara Ācārya. The conclusion is that the Supreme Personality of Godhead is situated in everyone’s heart, and His pure devotees, the Vaiṣṇavas, are also traveling all over the world, but those who are under the modes of material nature cannot understand the form of the Supreme Personality of Godhead, the source of this cosmic manifestation, or the Vaiṣṇavas. It is said, therefore, that one cannot see the Supreme Personality of Godhead or a Vaiṣṇava with these material eyes. One has to purify his senses and engage in the service of the Lord. Then gradually one can realize who is the Supreme Personality of Godhead and who is a Vaiṣṇava.