Normally when God spoke to Moses and gave him an instruction, God said “tell,” “speak” or “instruct.” This time, God told Moses to “command” Aaron.
The relationship that God wants with you is a relationship that responds and grows. If we respond and grow, we are like a tree that will produce good fruit. If we don’t grow and respond, we won’t produce good fruit. The High Priest is supposed to encourage the relationship between God and His people produce good fruit for eternity.
When God commands one to do something, deviation from the instruction isn’t tolerated. The Torah reading צו Tzav (“command,” Lev. 6:8–8:36) includes detailed instructions on how the priests are to handle other people’s offerings, symbolizing their approach to God. The LORD told Aaron that doing this right matters, not just to the people, but to God.