Reference for Bava Batra 106:6
א"ר נחמן אמר רבה בר אבוה הבונה פלטרין גדולים בנכסי הגר ובא אחר והעמיד להן דלתות קנה מאי טעמא קמא לבני בעלמא הוא דאפיך
R. Nahman further said in the name of Rabbah b. Abbuha: If a man builds a large villa on the estate of a [deceased] proselyte and another man comes and fixes the doors, the latter becomes owner. Why is this? Because the first one merely deposited bricks there.<span class="x" onmousemove="('comment',' I.e., so long as the building is not completed, it is regarded merely as a heap of bricks. ');"><sup>9</sup></span> R. Dimi b. Joseph said in the name of R. Eleazar: If a man finds a villa already erected on the estate of a [deceased] proselyte, and he adds one coat of whitewash or mural decoration, he acquires ownership.<span class="x" onmousemove="('comment',' Because he has done something to improve the building. ');"><sup>10</sup></span>