Numbers 5:15

12 Say to the children of Israel, If any man's wife does wrong, sinning against him

13 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;

14 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:

15 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.

16 And the priest will make her come near and put her before the Lord;

17 And the priest will take holy water in a pot and put in it dust from the floor of the House;

18 And he will make the woman come before the Lord with her hair loose, and will put the meal offering, the offering of a bitter spirit, in her hands; and the priest will take in his hand the bitter water causing the curse;