Reference for Eruvin 18:9

אמר רבה בר רב הונא נראה מבחוץ ושוה מבפנים נידון משום לחי אמר רבה ומותבינן אשמעתין חצר קטנה שנפרצה לגדולה גדולה מותרת וקטנה אסורה מפני שהיא כפתחה של גדולה ואם איתא קטנה נמי תשתרי בנראה מבחוץ ושוה מבפנים

But [what you might contend is] that he did hear it and is not of the same opinion; [is it not then possible that] R'Hiyya also is not of the same opinion?<span class="x" onmousemove="('comment',' How then could the Baraitha cited be adduced as proof that the ruling it lays down is also the one upheld by R. Hiyya?');">²⁰</span> - What [a comparison is] this! It might well [be contended that] R'Johanan does not hold the same opinion [and that it was] for this reason that he did not teach it; but as regards R'Hiyya if it is a fact that he does not hold the same opinion, what need was there for him to teach it?<span class="x" onmousemove="('comment',' None whatever. Since, however, he did teach it, one may well conclude that he holds the same opinion.');">²¹</span> Rabbah son of R'Huna said: [A post that is] seen from without though it appears even from within is regarded as a valid side-post.<span class="x" onmousemove="('comment',' Cf. supra for notes.');">²²</span>

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