Reference for Yevamot 31:18
ורבי יהודה מטמא מפני שהם גרים וטועים מבין העובדי כוכבים טהורים והוינן בה
are levitically clean,<span class="x" onmousemove="('comment',' Only the menstrual blood of the daughters of Israel is levitically unclean; and no pure Israelites lived at Rekem. ');"><sup>32</sup></span> and R. Judah declares them unclean because [the people there] were proselytes though misguided;<span class="x" onmousemove="('comment',' Though they no longer observed the religious laws of Judaism they were once proselytes and as such their menstrual blood is levitically unclean as is the case with that of Israelites. ');"><sup>33</sup></span> [those that come] from the heathens<span class="x" onmousemove="('comment',' I.e., from localities where no Israelites live. ');"><sup>34</sup></span> are levitically clean.<span class="x" onmousemove="('comment',' Nid. 56b, Bek. 38b. ');"><sup>35</sup></span> And the difficult point was raised