SB 5.4.16
yadyapi sva-viditam sakala-dharmam brahmam guhyam brahmanair darsita-margena samadibhir upayair janatam anusasasa.
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Although Lord Rsabhadeva knew everything about confidential Vedic knowledge, which includes information about all types of occupational duties, He still maintained Himself as a ksatriya and followed the instructions of the brahmanas as they related to mind control, sense control, tolerance and so forth. Thus He ruled the people according to the system of varnasrama-dharma, which enjoins that the brahmanas instruct the ksatriyas and the ksatriyas administer to the state through the vaisyas and sudras.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Although Rsabhadeva knew all the Vedic instructions perfectly well, He nonetheless followed the instructions of the brahmanas in order to perfectly maintain the social order. The brahmanas would give advice according to the sastras, and all the other castes would follow. The word brahma means “perfect knowledge of all activities,” and this knowledge is very confidentially described in the Vedic literatures. Men trained perfectly as brahmanas should know all Vedic literature, and the benefit derived from this literature should be distributed to the general populace. The general populace should follow the perfect brahmana. In this way, one can learn how to control the mind and senses and thus gradually advance to spiritual perfection.