פירוש על בבא קמא 11:2

If, according to Rav, who says, etc. The Gemara is now searching for an application of the common characteristic method from which we learn a category of damage that is not specifically mentioned in the Torah. The Gemara suggested that one’s stone, knife or load which was left where the wind blew them away and brought them to a rest in a public domain might qualify. The Gemara said that if the owner relinquished ownership, that can be learned directly from bor and no other source is necessary. According to Shmuel, even if the owner did not relinquish ownership, that too can be derived from bor. In some texts of the Gemara it says: that if the owner relinquished ownership, according to Rav that can be learned directly from shor. See Tosafot 3b ד"ה משורו where he explains that according to Rav shor alone is an insufficient source and it is necessary to use bor as a second source for liability according to Rav. If so, the Gemara could not ask here: that according to Rav, they can be derived from shor, for they cannot be derived from shor alone. According to Rav they are a perfect example of what can and needs to be derived from the common characteristic.
We do not have this text as we explained earlier (3b תוספות ד"ה משורו).