Reference for Bava Metzia 186:2
איתיביה אלו הם אונסין ששומר שכר פטור עליהן כגון (איוב א, טו) ותפל שבא ותקחם ואת הנערים הכו לפי חרב אמר ליה התם בחזני מתא
Abaye protested, 'If so, had he entered the town when people generally enter it [leaving his charges alone], would he still be exempt?' — 'Yes', he replied. 'Then had he slept a little when other people sleep, would he also be exempt?' — 'Even so,' was his answer. Thereupon he raised an objection: The following are the accidents for which a paid bailee is not responsible: E.g., <i>And the Sabeans fell upon them</i> [sc. the oxen and asses], <i>and took them away; yea, they have slain the servants with the edge of the sword</i>!<span class="x" onmousemove="('comment',' Job I, 15: this proves that they are free from liability only for exceptional and unpreventable mishaps. ');"><sup>2</sup></span>