Reference for Eruvin 116:12
<big><strong>מתני׳</strong></big> אין מודדין אלא מן המומחה ריבה למקום א' ומיעט למקום אחר שומעין למקום שריבה ריבה לאחד ומיעט לאחד שומעין למרובה
nor in those around the cities of refuge.<span class="x" onmousemove="('comment',' Supra 35b q.v. notes.');"><sup>21</sup></span> because these are ordinances of the Torah.<span class="x" onmousemove="('comment',' Which require exact measurements. No estimates or approximate calculations being allowed, slopes of hills or dales must be carefully measured cubit by cubit as level ground. vjnunv in vjn iht vjnun');"><sup>22</sup></span> <big><b>MISHNAH: </b></big>[THE SABBATH LIMIT OF A TOWN] IS MEASURED ONLY ALONG THE BEATEN TRACK.<span class="x" onmousemove="('comment',' Reading , the noun being derived from rt. 'to strike' (R. Han. Cf. Tosaf. s.v. a.l.) . Var. lec. 'expert', 'skilled d" v="" surveyor'="" (cf.="" rashi="" s.v.="" a.l.)="" .');"=""><sup>23</sup></span>