Commentary for Kiddushin 46:9

R. Elazar says that the third party cannot really say “on condition that your master has no right to it.” All would agree that such a condition does not prevent the master from gaining rights to the money acquired by the slave. R. Meir and the rabbis rather disagree about a case where the third party says “on condition that with it you go free.” To R. Meir this still does not work and the master acquires it immediately. The other rabbis hold that this works because the third party did not transfer ownership of the maneh to the slave—he only gave it to the slave for the slave to free himself. Since the slave has not come into possession of the maneh, he is able to use it become emancipated.