SB 10.1.2
yados ca dharma-silasya
nitaram muni-sattama
tatramsenavatirnasya
visnor viryani samsa nah
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
O best of munis, you have also described the descendants of Yadu, who were very pious and strictly adherent to religious principles. Now, if you will, kindly describe the wonderful, glorious activities of Lord Visnu, or Krsna, who appeared in that Yadu dynasty with Baladeva, His plenary expansion.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
The Brahma-samhita (5.1) explains that Krsna is the origin of the visnu-tattva.
isvarah paramah krsnah
sac-cid-ananda-vigrahah
anadir adir govindah
sarva-karana-karanam
“Krsna, who is known as Govinda, is the supreme controller. He has an eternal, blissful, spiritual body. He is the origin of all. He has no other origin, for He is the prime cause of all causes.”
yasyaika-nisvasita-kalam athavalambya
jivanti loma-vilaja jagad-anda-nathah
visnur mahan sa iha yasya kala-viseso
govindam adi-purusam tam aham bhajami
“The Brahmas, the heads of the innumerable universes, live only for the duration of one breath of Maha-Visnu. I worship Govinda, the original Lord, of whom Maha-Visnu is but a portion of a plenary portion.” (Brahma-samhita 5.48)
Govinda, Krsna, is the original Personality of Godhead. Krsnas tu bhagavan svayam. Even Lord Maha-Visnu, who by His breathing creates many millions upon millions of universes, is Lord Krsna’s kala-visesa, or plenary portion of a plenary portion. Maha-Visnu is a plenary expansion of Sankarsana, who is a plenary expansion of Narayana. Narayana is a plenary expansion of the catur-vyuha, and the catur-vyuha are plenary expansions of Baladeva, the first manifestation of Krsna. Therefore when Krsna appeared with Baladeva, all the visnu-tattvas appeared with Him.
Maharaja Pariksit requested Sukadeva Gosvami to describe Krsna and His glorious activities. Another meaning may be derived from this verse as follows, Although Sukadeva Gosvami was the greatest muni, he could describe Krsna only partially (amsena), for no one can describe Krsna fully. It is said that Anantadeva has thousands of heads, but although He tries to describe Krsna with thousands of tongues, His descriptions are still incomplete.