SB 8.5.29

ya eka-varṇaṁ tamasaḥ paraṁ tad
 alokam avyaktam ananta-pāram
āsāṁ cakāropasuparṇam enam
 upāsate yoga-rathena dhīrāḥ
Synonyms: 
yaḥ — the Supreme Personality of Godhead who; eka-varṇam — absolute, situated in pure goodness; tamasaḥ — to the darkness of the material world; param — transcendental; tat — that; alokam — who cannot be seen; avyaktam — not manifested; ananta-pāram — unlimited, beyond the measurement of material time and space; āsām cakāra — situated; upa-suparṇam — on the back of Garuḍa; enam — Him; upāsate — worship; yoga-rathena — by the vehicle of mystic yoga; dhīrāḥ — persons who are sober, undisturbed by material agitation.
Translation: 
The Supreme Personality of Godhead is situated in pure goodness [śuddha-sattva], and therefore He is eka-varṇa — the oṁkāra [praṇava]. Because the Lord is beyond the cosmic manifestation, which is considered to be darkness, He is not visible to material eyes. Nonetheless, He is not separated from us by time or space, but is present everywhere. Seated on His carrier, Garuḍa, He is worshiped by means of mystical yogic power by those who have achieved freedom from agitation. Let us all offer our respectful obeisances unto Him.
Purport: 

Sattvaṁ viśuddhaṁ vasudeva-śabditam (Bhāg. 4.3.23). In this material world, the three modes of material nature — goodness, passion and ignorance — prevail. Among these three, goodness is the platform of knowledge, and passion brings about a mixture of knowledge and ignorance, but the mode of ignorance is full of darkness. Therefore the Supreme Personality of Godhead is beyond darkness and passion. He is on the platform where goodness or knowledge is not disturbed by passion and ignorance. This is called the vasudeva platform. It is on this platform of vasudeva that Vāsudeva, or Kṛṣṇa, can appear. Thus Kṛṣṇa appeared on this planet as the son of Vasudeva. Because the Lord is situated beyond the three modes of material nature, He is unseen by those who are dominated by these three modes. One must therefore become dhīra, or undisturbed by the modes of material nature. The process of yoga may be practiced by one who is free from the agitation of these modes. Therefore yoga is defined in this way: yoga indriya-saṁyamaḥ. As previously explained, we are disturbed by the indriyas, or senses. Moreover, we are agitated by the three modes of material nature, which are imposed upon us by the external energy. In conditional life, the living entity moves turbulently in the whirlpool of birth and death, but when one is situated on the transcendental platform of viśuddha-sattva, pure goodness, he can see the Supreme Personality of Godhead, who sits on the back of Garuḍa. Lord Brahmā offers his respectful obeisances unto that Supreme Lord.