Reference for Bava Batra 107:8
איתמר שדה המסויימת במצריה אמר רב הונא אמר רב כיון שהכיש בה מכוש אחד קנה כולה ושמואל אמר לא קנה אלא מקום מכושו בלבד
Rab said: If a man draws a figure [of an animal or bird]<span class="x" onmousemove="('comment',' Not necessarily of the size of a cubit, as would be required in the case of any other ornamental figure. V. supra 53b. ');"><sup>10</sup></span> on the property of a [deceased] proselyte, he acquires ownership. [We ascribe this opinion to Rab] because Rab acquired the garden adjoining his <i>Beth Hamidrash</i> only by drawing a figure.<span class="x" onmousemove="('comment',' I.e., the garden adjoining his Beth Hamidrash belonged to a proselyte who died, and Rab acquired ownership by drawing the figure of an animal or bird on the wall of his house. ');"><sup>11</sup></span> It has been stated: If a field<span class="x" onmousemove="('comment',' The reference is to a field belonging to a deceased proselyte. In a case of sale, the digging of one spadeful is effective. ');"><sup>12</sup></span> has a boundary marked all round R. Huna says in the name of Rab that as soon as a man digs up one spadeful he becomes the legal owner. Samuel, however, said that he becomes the owner only of as much as he turns up.