Halakhah for Eruvin 101:18

אמר רב נחמן מחלוקת במקומי דר"מ סבר עיקר עירוב בפת

R'Aha B'Jacob ruled: A man who carries an object<span class="x" onmousemove="('comment',' On the Sabbath.');">⁵²</span> along four cubits in a public domain incurs no guilt unless he carries It a distance equal to the diagonal of their square.<span class="x" onmousemove="('comment',' Lit., 'they and their diagonal', i.e., the man is given the benefit of the corners, in agreement with the view of the Rabbis as explained by R. Hanina.');">⁵³</span> R'Papa related: Raba tested us [with the following question] 'With regard to a pillar in a public domain ten handbreadths high and four handbreadths wide, is it necessary<span class="x" onmousemove="('comment',' In order that it may be regarded as a private domain, v. supra 33b.');">⁵⁴</span> that its width shall be equal to the diagonal of four cubits square, or is this unnecessary'? And we replied: 'Is not this case identical with that o R'Hanina who learned:<span class="x" onmousemove="('comment',' So MS.M. Cur. edd. 'Hanania, because it was taught: R. Hanania said'.');">⁵⁵</span> Like this measurement<span class="x" onmousemove="('comment',' The one for the land of the Levites (Num. XXXV, 5) . vzf');">⁵⁶</span> shall be that of all who observe the Sabbath rest'.<span class="x" onmousemove="('comment',' on the various interpretations of this ruling cf. Tosaf. s.v. a.l.');">⁵⁷</span> THIS IT IS OF WHICH THE RABBIS HAVE SAID: A POOR MAN MAY MAKE HIS 'ERUB WITH HIS FEET. R'MEIR SAID: WE CAN APPLY THIS LAW TO A POOR MAN ONLY etc. R'Nahman said: They<span class="x" onmousemove="('comment',' R. Meir and R. Judah.');">⁵⁸</span> differ only where [the expression used was] 'In my place',<span class="x" onmousemove="('comment',' Sc. if the man appointed as his Sabbath base the place where he stood at the time. Only in such a case does R. Judah allow a rich man the same privilege as to a poor mall.');">⁵⁹</span> since R'Meir holds that the essence of an 'erub is bread

Shulchan Arukh, Orach Chayim