Reference for Bava Metzia 51:5

תנא אם היה כותל ממולא מהן חולקין פשיטא לא צריכא דמשפע בחד גיסא מהו דתימא אשתפוכי אישתפוך קמ"ל:

But is that not obvious? — It is necessary [to state this] only when it [the cavity or the wall] slopes to one side: I might have thought that it [the article found there] had slid down.<span class="x" onmousemove="('comment',' But was originally at the upper portion of the cavity, and the ownership should be determined accordingly. ');">⁵</span>

Jastrow