SB 8.5.27
vipascitam prana-mano-dhiyatmanam
arthendriyabhasam anidram avranam
chayatapau yatra na grdhra-paksau
tam aksaram kham tri-yugam vrajamahe
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
The Supreme Personality of Godhead directly and indirectly knows how everything, including the living force, mind and intelligence, is working under His control. He is the illuminator of everything and has no ignorance. He does not have a material body subject to the reactions of previous activities, and He is free from the ignorance of partiality and materialistic education. I therefore take shelter of the lotus feet of the Supreme Lord, who is eternal, all-pervading and as great as the sky and who appears with six opulences in three yugas [Satya, Treta and Dvapara].
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
In the beginning of Srimad-Bhagavatam the Supreme Personality of Godhead is described in this way: janmady asya yato ’nvayad itaratas carthesv abhijñah. The Lord is the origin of all emanations, and He directly and indirectly knows everything about all the activities within His creation. Therefore the Lord is addressed here as vipascitam, one who is full of all knowledge or who knows everything. The Lord is the Supreme Soul, and He knows everything about the living entities and their senses.
The word anidram, meaning “always awake and free from ignorance,” is very important in this verse. As stated in Bhagavad-gita (15.15), mattah smrtir jñanam apohanam ca: it is the Lord who gives intelligence to everyone and who causes everyone to forget. There are millions and millions of living entities, and the Lord gives them directions. Therefore He has no time to sleep, and He is never in ignorance of our activities. The Lord is the witness of everything; He sees what we are doing at every moment. The Lord is not covered by a body resulting from karma. Our bodies are formed as a result of our past deeds (karmana daiva-netrena), but the Supreme Personality of Godhead does not have a material body, and therefore He has no avidya, ignorance. He does not sleep, but is always alert and awake.
The Supreme Lord is described as tri-yuga because although He appeared variously in Satya-yuga, Treta-yuga and Dvapara-yuga, when He appeared in Kali-yuga He never declared Himself the Supreme Personality of Godhead.
krsna-varnam tvisakrsnam
sangopangastra-parsadam
The Lord appears in Kali-yuga as a devotee. Thus although He is Krsna, He chants the Hare Krsna mantra like a devotee. Still, Srimad-Bhagavatam (11.5.32) recommends:
yajñaih sankirtana-prayair
yajanti hi sumedhasah
Sri Caitanya Mahaprabhu, whose complexion is not black like that of Krsna but is golden (tvisakrsnam), is the Supreme Personality of Godhead. He is accompanied by associates like Nityananda, Advaita, Gadadhara and Srivasa. Those who are sufficiently intelligent worship this Supreme Personality of Godhead by performing sankirtana-yajña. In this incarnation, the Supreme Lord declares Himself not to be the Supreme Lord, and therefore He is known as Tri-yuga.