Reference for Bava Metzia 28:17
אמר רבא הכא במאי עסקינן כגון שגזל שדה מחבירו [מלאה פירות ואכל את הפירות וחפר בה בורות שיחין ומערות בא נגזל לגבות קרן גובה מנכסים משועבדים בא נגזל לגבות פירות גובה מנכסים בני חורין
and does it not mean that [he] only [collects it from] an improved field but not from the produce [of the field]? It is therefore obvious that it refers to one who acquired [a field] wrongfully and to the one who has been deprived of it,<span class="x" onmousemove="('comment',' The produce of the field or the improvement therein may be claimed by the original owner who was robbed of his property, no matter whether the produce was there when the field was first taken away, or not. The owner can always claim the land with all its improvements, except that the buyer may demand back his outlay which brought about the improved condition of the field, provided that the sum demanded by the buyer does not exceed the amount by which the value of the field was increased as a result of the improvements. ');"><sup>15</sup></span>