Reference for Pesachim 4:12

ואידך הרחקה הוא דעבוד רבנן לדאורייתא

of dawn: this is R'Eliezer B'Jacob's view. R'Simeon maintained: Until cockcrow.<span class="x" onmousemove="('comment',' The prohibition of work on the fourteenth is likewise merely Rabbinical.');">¹³</span>

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