סוטה

הַמְקַנֵּא לְאִשְׁתּוֹ, רַבִּי אֱלִיעֶזֶר אוֹמֵר, מְקַנֵּא לָהּ עַל פִּי שְׁנַיִם, וּמַשְׁקָהּ עַל פִּי עֵד אֶחָד אוֹ עַל פִּי עַצְמוֹ. רַבִּי יְהוֹשֻׁעַ אוֹמֵר, מְקַנֵּא לָהּ עַל פִּי שְׁנַיִם וּמַשְׁקָהּ עַל פִּי שְׁנָיִם:

One who warns his wife [not to associate with a certain man]: Rabbi Eliezer says: he warns her on the testimony of two witnesses, and makes her drink [the bitter waters] on the testimony of one witness or on his own testimony. Rabbi Joshua says: he warns her on the testimony of two and makes her drink on the testimony of two.

כֵּיצַד מְקַנֵּא לָהּ. אָמַר לָהּ בִּפְנֵי שְׁנַיִם, אַל תְּדַבְּרִי עִם אִישׁ פְּלוֹנִי, וְדִבְּרָה עִמּוֹ, עֲדַיִן הִיא מֻתֶּרֶת לְבֵיתָהּ וּמֻתֶּרֶת לֶאֱכֹל בַּתְּרוּמָה. נִכְנְסָה עִמּוֹ לְבֵית הַסֵּתֶר וְשָׁהֲתָה עִמּוֹ כְדֵי טֻמְאָה, אֲסוּרָה לְבֵיתָהּ וַאֲסוּרָה לֶאֱכֹל בַּתְּרוּמָה. וְאִם מֵת, חוֹלֶצֶת וְלֹא מִתְיַבָּמֶת:

How does he warn her? If he says to her in front of two [witnesses], “Do not speak with that man”, and she spoke with him, she is still permitted to her husband and permitted to eat terumah. If she entered a private place with him and stayed with him a time sufficient for her to be defiled [by having sexual intercourse with him], she is forbidden to her husband and forbidden to eat terumah. If [her husband] died, she performs halitzah but cannot contract yibbum.