Commentary for Kiddushin 45:12

We might have thought, as we tried to propose in yesterday’s section, that when it says that he may free himself it means “even through his own agency,” and then say that what this teaches us is that his right to acquire money and his freedom come simultaneously. Thus he can acquire the money to use to buy himself free. But the problem is that the end of this clause in the mishnah teaches that when it comes to the document, the slave can become free by a document accepted by others, but not by one that he himself accepts. The problem is that we hold that his freedom and his ability to accept a document also come simultaneously. This means that he should be able to accept his own deed of emancipation.