Responsa for Bava Batra 94:6

ורב ביבי מסיים בה משמיה דרב נחמן קרקע אין לו אבל מעות יש לו במה דברים אמורים שאמרו עדים בפנינו מנה לו אבל אמרו עדים בפנינו הודה לו לא כדרב כהנא דאמר אי לאו דאודי ליה הוה ממטי ליה לדידיה ולחמריה לשחוור

R. Bibi quoted R. Nahman as adding to the statement [which he had made in the name of R. Huna]: Though the robber has no title to the land [which he has forcibly taken], he has a title to the money [which he may have given in consideration of it].<span class="x" onmousemove="('comment',' I.e., if the robber has given the owner money in payment of the field, when the latter recovers the field he must refund the money. ');">¹¹</span> And this is only the case if witnesses testify: We saw him counting out the money [to the original owner]. but if they merely testify: We heard the original owner admit to him [that he had received money], the robber cannot recover it, for the reason given by R. Kahana, that if he had not made this admission to him the other would have handed him and his ass over to the town prefect.<span class="x" onmousemove="('comment',' The admission therefore is presumably false. ');">¹²</span>

Teshuvot Maharam