Reference for Pesachim 57:4

רבא אמר לעולם רבי שמעון היא ורבי שמעון קנסא קניס הואיל ועבר עליה בבל יראה ובל ימצא

Again, logically he ought to teach that even during its period it<span class="x" onmousemove="('comment',' The leaven of a Gentile.');">⁵</span> is permitted for use, but because he mentions after its period in connection with that of an Israelite, he also teaches about that of a heathen after its period.

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