SB 5.4.16

yadyapi sva-viditaṁ sakala-dharmaṁ brāhmaṁ guhyaṁ brāhmaṇair darśita-mārgeṇa sāmādibhir upāyair janatām anuśaśāsa.
Word for word: 
yadyapi — although; sva-viditam — known by Him; sakala-dharmam — which includes all different types of occupational duties; brāhmam — Vedic instruction; guhyam — very confidential; brāhmaṇaiḥ — by the brāhmaṇas; darśita-mārgeṇa — by the path showed; sāma-ādibhiḥ — sāma, dama, titikṣā (controlling the mind, controlling the senses, practicing tolerance) and so on; upāyaiḥ — by the means; janatām — the people in general; anuśaśāsa — he ruled over.
Translation: 
Although Lord Ṛṣabhadeva knew everything about confidential Vedic knowledge, which includes information about all types of occupational duties, He still maintained Himself as a kṣatriya and followed the instructions of the brāhmaṇas as they related to mind control, sense control, tolerance and so forth. Thus He ruled the people according to the system of varṇāśrama-dharma, which enjoins that the brāhmaṇas instruct the kṣatriyas and the kṣatriyas administer to the state through the vaiśyas and śūdras.
Purport: 

Although Ṛṣabhadeva knew all the Vedic instructions perfectly well, He nonetheless followed the instructions of the brāhmaṇas in order to perfectly maintain the social order. The brāhmaṇas would give advice according to the śāstras, 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 brāhmaṇas 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 brāhmaṇa. In this way, one can learn how to control the mind and senses and thus gradually advance to spiritual perfection.