Leviticus 10:12

And Moses spake unto Aaron, and unto Eleazar and unto Ithamar, his sons that were left, take the meat-offering that remaineth of the offerings of the Lord made by fire, only a handful having been offered, Leviticus 9:17, and eat it without leaven beside the altar; for it is most holy. It was used as food for the priests in a place provided for that purpose in the court.

And ye shall not swear by My name falsely; true oaths are indeed permitted, those in the interest of one's neighbor, but not false oaths; neither shalt thou profane the name of thy God, desecrate it by taking it in vain. I am the Lord.