Reference for Bava Kamma 64:17

בלילה נמי איבעי ליה עיוני בסותר את כותלו ביום לאשפה

Our Rabbis taught: 'If a man entered the workshop of a joiner without permission and a chip of wood flew off and struck him in the face and killed him, he [the joiner] is exempt.<span class="x" onmousemove="('comment',' From fleeing to the city of refuge. Cf. Num. XXXV, 11-28, Deut. XIX, 4-6; and supra p. 137. ');">⁷</span>

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