Exodus 27:21 "In the tent of meeting, outside the veil which is before the testimony, Aaron and his sons shall keep it in order from evening to morning before the LORD; it shall be a perpetual statute throughout their generations for the sons of Israel.

Leviticus 24:3 "Outside the veil of testimony in the tent of meeting, Aaron shall keep it in order from evening to morning before the LORD continually; it shall be a perpetual statute throughout your generations.

Numbers 16:46 Moses said to Aaron, "Take your censer and put in it fire from the altar, and lay incense on it; then bring it quickly to the congregation and make atonement for them, for wrath has gone forth from the LORD, the plague has begun!" (NASB ©1995)