Malachi says the priest’s lips should guard knowledge, and people should seek instruction from his mouth Malachi 2:7. The priest is called the messenger of the LORD of hosts Malachi 2:7. This is contrasted with priests who caused many to stumble by their instruction Malachi 2:8.
In Malachi 2:5–7, the speaker recalls an earlier model priest who lived inside God’s covenant. That covenant brought “life and peace,” and it produced reverence for God’s name. The model priest’s speech matched truth: reliable instruction came from his mouth, and wrongdoing was not on his lips. These verses sit inside a larger rebuke of priests for dishonoring God and corrupting worship and teaching (2:1–9). The passage works by contrast: it sets an ideal picture of priestly speech and conduct in the past, then uses that picture as the standard by which the present priesthood is measured.
Malachi 2:5–7 looks back to a “model” priest as a standard for what priestly speech and leadership were meant to be. The text presents God’s covenant with that priest as bringing “life and peace” (explicit claim), and it connects those gifts with the priest’s reverence for God’s name (explicit claim).
A careful answer keeps the immediate passage, the book's argument, and the whole-Bible storyline together, so the question is answered in context instead of as a detached idea.
Start with Malachi 2:7, then read the surrounding section so the answer stays connected to the passage's flow.
7For the priest`s lips should keep knowledge, and they should seek the law at his mouth; for he is the messenger of Yahweh of Hosts.