Jerusalem Talmud Yevamot 4.10

משנה: שׁוֹמֶרֶת יָבָם שֶׁקִּידֵּשׁ אָחִיו אֶת אֲחוֹתָהּ. מִשּׁוּם רִבִּי יְהוּדָה בֶּן בָּתֵירָה אָמְרוּ. אוֹמֵר לוֹ הַמְתֵּן עַד שֶׁיַּעֲשֶׂה אָחִיךָ הַגָּדוֹל מַעֲשֶׂה. חָלְצוּ לָהּ אַחִין אוֹ כָּנְסוּ יִכְנוֹס אֶת אִשְׁתּוֹ. מֵתֶה הַיְּבָמָה יִכְנוֹס. מֵת הַיָּבָם מוֹצִיא אֶת אִשְׁתּוֹ בְגֵט וְאֵשֶׁת אָחִיו בַּחֲלִיצָה.

MISHNAH: If a brother gave qiddushin to the sister of a woman waiting for the levir, they said in the name of Rebbi Jehudah ben Bathyra: One says to him wait until your older brother has acted. If [one of the] brothers performed ḥalîṣah or married her, he may marry his wife. If the sister-in-law died, he may marry. If the levir died, he has to remove himself from his wife by a bill of divorce and his brother’s widow by ḥalîṣah.

הלכה: שׁוֹמֶרֶת יָבָם כול׳. לֹא אָמְרוּ אֶלָּא מֵתָה יְבִמְתּוֹ מוּתָּר בְּאִשְׁתּוֹ. אֲבָל אִם מֵתָה אִשְׁתּוֹ אָסוּר בִּיבִמְתּוֹ. אָמַר רִבִּי יוֹחָנָן. זוֹ דִבְרֵי רִבִּי לִעֶזֶר. אֲבָל דִּבְרֵי חֲכָמִים מֵתָה יְבִמְתּוֹ מוּתָּר בְּאִשְׁתּוֹ. מֵתָה אִשְׁתּוֹ מוּתָּר בִּיבִמְתּוֹ. אָמַר רִבִּי יוֹחָנָן. דִּבְרֵי חֲכָמִים. כָּל דָּבָר שֶׁהוּא בָא מַחְמַת הַגּוֹרֵם בָּטַל הַגּוֹרֵם בָּטַל הָאִיסּוּר. וְדִבְרֵי רִבִּי לִעֶזֶר. אַף עַל פִּי שֶׁבַּטַּל הַגּוֹרֵם הָאִיסּוּר בִּמְקוֹמוֹ.

HALAKHAH: It says only: If the sister-in-law died, his wife is permitted to him. But if his wife died, his sister-in-law is forbidden to him. Rebbi Joḥanan said, these are the words of Rebbi Eliezer. But the Sages say, if his sister-in-law died, his wife is permitted to him, if his wife died, his sister-in-law is permitted to him. Rebbi Joḥanan said, the Sages hold that for anything induced by a cause, if the cause is removed the prohibition is removed. But for Rebbi Eliezer, if the cause is removed the prohibition remains.