Reference for Chullin 273:21

לכדתנא דבי ר' ישמעאל דתנא דבי ר' ישמעאל

The expression 'to stand to minister'<span class="x" onmousemove="('comment',' Deut. XVIII, 5. This verse follows immediately after the one enjoining the law of the first fleece.');">¹⁶</span>

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