Reference for Eruvin 72:2
אמר רב פפא אפילו תימא תחילת היום קונה עירוב בעינן סעודה הראויה מבעוד יום וליכא:
that the validity of an 'erub takes effect at the beginning of the [Sabbath] day, yet [the contents of the lagin are unfit as an 'erub since] it is essential to have a meal th suitable for consumption while it is yet day,<span class="x" onmousemove="('comment',' I.e., at the beginning of twilight.');"><sup>4</sup></span> which is not the case here.<span class="x" onmousemove="('comment',' Because at that time the contents of the lagin were still tebel.');"><sup>5</sup></span> <big><b>MISHNAH: </b></big>A MAN MAY ATTACH A CONDITION TO HIS ERUB AND<span class="x" onmousemove="('comment',' Depositing two 'erubs, one at a distance of two thousand cubits from the east side of his house and another in the opposite direction at a distance of two thousand cubits from the west of his house.');"><sup>6</sup></span>