Reference for Pesachim 187:4

אמר רבא שיתא אלפי פרסי הוי עלמא וסומכא דרקיעא אלפא פרסי חדא גמרא וחדא סברא

Therefore It is stated, 'and is not in a journey,' and lo, he was not in a journey.<span class="x" onmousemove="('comment',' He should have completed it on foot.');">⁵</span> Raba said: The world is six thousand parasangs,<span class="x" onmousemove="('comment',' Rashi: in diameter from east to west.');">⁶</span>

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