Numbers 5
19 Ref And the priest shall cause her to swear, and shall say unto the woman, If no man have lain with thee, and if thou have not gone aside to uncleanness, being under thy husband, be thou free from this water of bitterness that causeth the curse.
20 Ref But if thou have gone aside, being under thy husband, and if thou be defiled, and some man have lain with thee besides thy husband: