Numbers 16:46-47

46Moses said to Aaron, “Take a censer and put fire in it 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!”

47So Aaron took the burning censer as Moses commanded, and ran into the midst of the assembly; and behold, the plague had [already] begun among the people; and he put on the incense and made atonement for the people.