Reference for Chullin 271:21

למעוטי בתי כנסיות ובתי מדרשות

[from which it would follow that] thine only is subject but not what is held jointly, the Divine Law stated: If any man fall from thence.<span class="x" onmousemove="('comment',' Ibid. Any roof from which one might fall had to be fenced, even though the roof was held jointly.');">¹⁷</span>

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