Related for Berakhot 3:6
זָב שֶׁרָאָה קְרִי, וְנִדָּה שֶׁפָּלְטָה שִׁכְבַת זֶרַע, וְהַמְשַׁמֶּשֶׁת שֶׁרָאֲתָה נִדָּה, צְרִיכִין טְבִילָה, וְרַבִּי יְהוּדָה פּוֹטֵר:
A zav (one suffering from a genital flow) who discharged semen, a niddah who emitted semen, and a woman who had intercourse and became a niddah must undergo ritual immersion. [A zav who discharged semen: Though he is unclean seven days because of zav uncleanliness, and this immersion does not render him clean, still, he must undergo this immersion for words of Torah because of the semen discharge, as instituted by Ezra. Likewise, a niddah who wishes to pray and emits semen (from a prior intercourse) is regarded as one discharging semen. And such an emission of semen renders a woman unclean for three days after intercourse. After that time it putrefies in her body and is no longer viable. And it is to be understood thus: "A niddah who emitted, now, semen from an intercourse prior to her becoming a niddah, and a woman who had intercourse — one who, after intercourse, became a niddah — must undergo ritual immersion.] And R. Yehudah does not require it. [R. Yehudah does not require it even in the instance of a woman who after intercourse became a niddah, even though ab initio she must undergo ritual immersion and it can be contended that the immersion obligation does not leave her. And we have already written above that this immersion ordinance was rescinded, being "an ordinance by which the majority of the congregation cannot abide."]