Reference for Sanhedrin 80:9

אלא אמר רב יהודה (דברים יג, טו) והנה אמת נכון והנה אמת נכון הא חד סרי שבע לשבע חקירות דל תלת לגזירה שוה פשא להו חדא

And they shall inquire and they shall search,<span class="x" onmousemove="('comment',' Which is the expression used in respect of a condemned city. ');">¹⁷</span> and yet changes its expression [by employing the word] 'diligently',<span class="x" onmousemove="('comment',' I.e., instead of 'they shall search', the second question was expressed by 'diligently'. ');">¹⁸</span>

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