Leviticus 1:9
But his inwards and his legs shall he wash in water: and the priest shall burn all on the altar, to be a burnt sacrifice, an offering made by fire, of a sweet savour unto the LORD. But his inwards and his legs shall he wash in water: and the priest shall burn all on the altar, to be a burnt sacrifice, an offering made by fire, of a sweet savour unto the LORD.
The instructions were given by Christ through Moses as part of the directions for the sacrificial service. They required the inwards and the legs of the offering to be washed in water, after which the priest was to burn the whole offering on the altar. These outward acts were not meaningless forms, for the sacrificial system represented Christ's ministry and His death. The offering pointed to the Saviour who would bear the sins of the world and die for its redemption.