Reference for Bava Batra 185:3

ת"ש שור שנגח את הפרה ונמצא עוברה בצדה ואינו ידוע אם עד שלא נגחה ילדה או אם משנגחה ילדה משלם חצי נזק לפרה ורביע לולד

[If] an ox gored a cow, and its embryo was found [dead] at its side, and it is not known whether it gave birth before it was gored<span class="x" onmousemove="('comment',' In which case the owner of the ox is free from all liability. ');">⁵</span> or after it was gored,<span class="x" onmousemove="('comment',' And, consequently, death was caused by the goring, and the owner of the ox is responsible. ');">⁶</span>

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