Reference for Sanhedrin 152:15

כבש מנלן אמר שמואל דאמר קרא (במדבר לה, כא) או באיבה לרבות את המצמצם

<b><i>GEMARA</i></b>. Samuel said: why is 'hand' not mentioned in connection with iron?<span class="x" onmousemove="('comment',' In Num. XXXV, 16-18, dealing with murder, iron, stone, and wooden weapons are enumerated: 'hand' is used in connection with the latter two, implying that they must be large enough to afford a hold to the hand, but not in connection with the first. ');">¹³</span>

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