Reference for Shabbat 194:4

דתניא מרה"י לרשות הרבים ועבר ארבע אמות ברה"ר רבי יהודה מחייב וחכמים פוטרין

in reference to this, and so find Rabbi self-contradictory; We learn it in reference to R. Judah['s ruling]. and find no difficulty.<span class="x" onmousemove="('comment',' For we find nowhere that R. Judah exempts for a derivative performed conjointly with the principal. ');">⁴</span>

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