1,987. Witnesses Who Contradict
Hilchos Sotah 1:16
If one valid witness testifies that the woman committed adultery, she is not made to drink the bitter water, as we have discussed. If a second witness arrives and contradicts the first, saying that the woman didn’t commit adultery, the second witness’ testimony is not accepted. This is because when it comes to the suspected woman, the testimony of a lone witness is considered equal to that of two witnesses. Therefore, the testimony of the second, lone witness cannot overturn that of the first, which is considered to be equal to that of two witnesses.
Hilchos Sotah 1:17
If both lone witnesses come at the same time, one testifying that the woman committed adultery and the other that she didn’t, or if one witness testifies that she committed adultery and two others testify that she didn’t, then she is made to drink the bitter water.