פירוש על בבא קמא 7:18

And according to your reasoning. Shmuel questioned Rav; the Mishna says about the avos, it is your obligation to guard them, this term does not seem to refer to a person. It is a person’s obligation to guard himself, not to guard them. Rav responds: and according to your reasoning, you have the same problem. What is Shmuel’s reasoning, that Rav to which Rav refers?
The explanation is: even if you say that maveh in our Mishna is shain, the term “and it is your obligation to guard them” makes sense in out Mishna, but that term is used in Karno’s Braita where a person is specifically mentioned among the avos, and even so he uses the term “and it is your obligation to guard them”. How will you deal with the term “and it is your obligation to guard them” there.

[For a] man [the responsibility for] safeguarding his body is upon him. The Gemara only seems to have a problem with one term that the Mishna uses “and it is your obligation to guard them”. Otherwise, there is nothing in the Mishna that presents a problem to Rav who says that maveh is a person.
From this question, it appears that we do not have in our Mishna the text וממונא -- and it is your property, since the Gemara does not also ask; is a person his own property? As the Gemara is asking how Rav’s position is compatible with the Mishna, this question should also have been raised.
Tosafot is not convinced of the severity of this problem.
And for this reason, that the Gemara did not raise the question, it need not be erased, as I have explained earlier.¹Tosafot explained earlier that since aish and bor are also not one’s property the Mishna’s usage of the term ממונך -- your property, is obviously not accurate.