כִּ֤י תִבְנֶה֙ בַּ֣יִת חָדָ֔שׁ וְעָשִׂ֥יתָ מַעֲקֶ֖ה לְגַגֶּ֑ךָ וְלֹֽא־תָשִׂ֤ים דָּמִים֙ בְּבֵיתֶ֔ךָ כִּֽי־יִפֹּ֥ל הַנֹּפֵ֖ל מִמֶּֽנּוּ׃ (ס)
你若建造新房屋，就要在房頂四周安設欄杆，免得有人從上面掉下來，流血的罪就歸於你的家。
Collected Responsa to Chaplains
In addition to these dangers with regard to which one should avoid exposing himself, there are also the dangers concerning which one should avoid exposing others. These are based upon the command (Deut. 22:8) to put a parapet around the roof of the house. This verse ends with: "Lo sosim domim b'vesecho," which becomes the key verse in all the later discussions. In the Sifre (ad loc.) this law is extended to similar neglect of safeguards, such as leaving a well uncovered, or leaving a stumbling block in the road. This duty to avoid causing danger to oneself and to others is codified in Maimonides (Hil. Rozeach XI, 4) and Shulchan Aruch, Choshen Mishpot 427.