Malachi 2:4-7

Then you will know [without any doubt] that I have sent this [new] commandment to you (priests), that My covenant may continue with Levi [the priestly tribe],” says the LORD of hosts. “My covenant with Levi was [one of] life and peace, and I gave them to him as an object of reverence; so he [and the priests] feared Me and stood in reverent awe of My name. True instruction was in Levi’s mouth and injustice was not found on his lips. He walked with Me in peace and uprightness, and he turned many from wickedness. For the lips of the priest should guard and preserve knowledge [of My law], and the people should seek instruction from his mouth; for he is the messenger of the LORD of hosts.