Numbers 5:11-15

And the Lord said to Moses, Say to the children of Israel, If any man's wife does wrong, sinning against him By taking as her lover another man, and keeps it secret so that her husband has no knowledge of it, and there is no witness against her, and she is not taken in the act; If the spirit of doubt comes into her husband's heart, and he has doubts of his wife, with good cause; or if he has doubts of her without cause: Then let him take her to the priest, offering for her the tenth part of an ephah of barley meal, without oil or perfume; for it is a meal offering of a bitter spirit, a meal offering keeping wrongdoing in mind.