Reference for Bava Batra 274:8

אמר רבא אמר רב נחמן שור זה נתון לך במתנה על מנת שתחזירהו לי הקדישו והחזירו ה"ז מוקדש ומוחזר

Raba said: [If one said to another,] 'This ethrog is given to you as a gift on the condition that you return it to me', [and the recipient] used it for its ritual purpose,<span class="x" onmousemove="('comment',' V. p. 581, n. 12. ');">¹⁵</span> then if he [subsequently] returned it, he is exempt;<span class="x" onmousemove="('comment',' I.e., he has properly performed his ritual obligation. ');">¹⁶</span>

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