Speak unto Aaron and to his sons, that they separate themselves from the holy things of the children of Israel, and that they profane not my holy name in those things which they hallow unto me: I am the Lord. (Leviticus 22:2)
All that served at the tabernacle must be strictly clean, ceremonially and otherwise. If any priest had become unclean, he must carefully avoid touching or even coming near any of the holy things. These included everything pertaining to the service of the sanctuary, such as the altars, with all their utensils, and also the offerings the people brought to the priests. If any did so, he was cut off from the presence of the Lord, that is, from the service of the tabernacle.