Ad regulam Catonianam liber singularis
Dig. 49,17,20Paulus libro singulari ad regulam Catonianam. Sed si ponas filium testamentum fecisse et patrem heredem instituisse: cum utique pater testamento suo servo filii libertatem dedisset, qui ad eum ex testamento filii pertinere coeperit, videndum est, numquid ei comparari debeat, qui, cum manumitteretur, alienus erat, deinde postea adquisitus est. sed favorabile est libertatem a patre relictam admittere: et ab initio patris esse eum videri ex hoc, quod postea contigit, ostenditur.
Paulus, On the Rule of Cato. If you suppose that a son has made a will, and appointed his father his heir, after the father by his will has granted freedom to his son’s slave, who began to belong to him by the will of his son, let us see whether this slave should be compared to one who belonged to another at the time he was manumitted, and the ownership of whom was afterwards acquired. It is favorable to freedom to admit that it was granted by the father, and to hold that the slave belonged to the latter from the beginning; which is shown from what afterwards occurred.