Reference for Bava Metzia 200:20

זה אומר איני יודע וזה אומר איני יודע יחלוקו: הא מני סומכוס היא דאמר ממון המוטל בספק חולקין

With whom does this agree? With Symmachus, who ruled: When the ownership of property is in doubt, it is divided. Then consider the latter clause: 'If each pleads, "It happened in my ownership," the vendor must swear that she bore whilst in his possession.' Now according to Rabbah son of R. Huna, who maintained: Indeed, Symmachus gave his ruling even where both make positive statements; why should he swear? Surely they ought to divide! — Symmachus admits [that one must swear] when an oath is required by Biblical law; [the circumstances being] that he [the owner] had cut off her [sc. the slave's] hand, and in accordance with Raba's explanation.<span class="x" onmousemove="('comment',' Supra p. 572. ');">¹⁹</span>

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