Study Sotah folio 18B with parallel Hebrew-English text, traditional commentary, and modern study tools. Free access to Babylonian Talmud online.
nor as a widow waiting for my yavam to perform levirate marriage, since a woman at that stage is prohibited from having sex with any men, nor when married through levirate marriage to the yavam; amen that I did not become defiled, and if I did become defiled, may all these curses come upon me.
R' Meir says that “amen, amen” means: Amen that I did not become defiled in the past, amen that I will not become defiled in the future.
All agree that he may stipulate with her through this oath neither with regard to what she did before becoming betrothed to him, nor with regard to what she will do after she becomes divorced from him.
Similarly, if a husband divorced his wife, and while divorced she secluded herself with another man and became defiled, and afterward her husband took her back and remarried her, and he then warned her about a specific man, and she secluded herself, and she is now about to drink the water of the sot
This is the principle: In every case where if she would have sex with someone else she would not become forbidden to her husband due to this act, he may not stipulate with her that her oath include that act. The oath can include only cases in which she would be rendered forbidden to him.