Reference for Bava Metzia 48:4
וכי מאחר דאסירא בהנאה מותרת משום מציאה למאי הלכתא אמר רב אשי לקנקנה:
A certain man once found four <i>zuz</i> which had been tied up in a cloth and thrown into the river Biran. When he appeared before Rab Judah the latter said to him, 'Go and announce it.' But is not this [like retrieving an object from] the tide of the sea? — The river Biran is different. As it contains obstacles<span class="x" onmousemove="('comment',' Various kinds of network intended to catch the fish. ');"><sup>9</sup></span> the owner does not give up hope.<span class="x" onmousemove="('comment',' As the network is likely to hold up the article floating in the river the owner hopes that the article will ultimately be recovered. ');"><sup>10</sup></span> But does not the majority<span class="x" onmousemove="('comment',' Of the inhabitants of the territory through which the river Biran flows. ');"><sup>11</sup></span>