Naso 

נשא

They gave the sota “bitter water” to drink. If she in fact had committed adultery, she would die an unusual death. If she had not committed adultery, she would be blessed. The Sages describe the potency of the water, as its mere vapor was enough to check if the woman had committed adultery.

There was an incident involving two sisters who resembled each other. One was married and living in one city, and the other was married and living in another city. The husband of one suspected his wife of adultery and sought to warn her, then have her drink the bitter [sota] water in Jerusalem. She went to that city in which her married sister was living. The latter said to her sister: Why did you come here? The visiting sister said to her: My husband wants me to drink the bitter sota water. Her sister said to her: I will go in your stead and drink. She said to her: Go. The other sister donned her sister’s garments and went in her stead. She drank the bitter <source>(Tanĥuma, Naso) </source>

They gave the sota “bitter water” to drink. If she in fact had committed adultery, she would die an unusual death. If she had not committed adultery, she would be blessed. The Sages describe the potency of the water, as its mere vapor was enough to check if the woman had committed adultery. 