[11] And Aaron shall offer the Levites before the LORD for an offering of the children of Israel, that they may execute the service of the LORD. [12] And the Levites shall lay their hands upon the heads of the bullocks: and thou shalt offer the one for a sin offering, and the other for a burnt offering, unto the LORD, to make an atonement for the Levites. [13] And thou shalt set the Levites before Aaron, and before his sons, and offer them for an offering unto the LORD.