pranebhyo ’ham ca jajñire
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
After 4,300,000,000 solar years, when Brahma awoke to create again by the will of the Lord, all the rsis like Marici, Angira, Atri and so on were created from the transcendental body of the Lord, and I also appeared along with them.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
The duration of a day in the life of Brahma is 4,320,000,000 solar years. This is stated also in the Bhagavad-gita. So for this period Brahmaji rests in yoga-nidra within the body of the Garbhodakasayi Visnu, the generator of Brahma. Thus after the sleeping period of Brahma, when there is again creation by the will of the Lord through the agency of Brahma, all the great rsis again appear from different parts of the transcendental body, and Narada also appears. This means that Narada appears in the same transcendental body, just as a man awakes from sleep in the same body. Sri Narada is eternally free to move in all parts of the transcendental and material creations of the Almighty. He appears and disappears in his own transcendental body, which is without distinction of body and soul, unlike conditioned beings.