Numbers 5:14-15

14If her husband becomes jealous and is suspicious of his wife and needs to know whether or not she has defiled herself,

15the husband must bring his wife to the priest. He must also bring an offering of two quarts of barley flour to be presented on her behalf. Do not mix it with olive oil or frankincense, for it is a jealousy offering—an offering to prove whether or not she is guilty.