[We begin with the first mishna on 28b.]
Mishna: If a person claims an item but does not give indentifying marks, he (the finder) should not give it to him. And a dishonest (claimant) -- even if he names identifying marks, (the finder) should not give it to him, as it is written, "Until your bro ther asks (d'rosh) for it" (Deut. 22:2) [means] until you investigate [tid'rosh] to see if he is a dishonest person or not. [We have already gone through the exegesis on page 27b.]
Gemara: It has been taught: Rav Yehuda says he announces a lost item (without specifying what the item was). Rav Nachman says he announces a garment (i.e., he specifies what item he found). Rav Yehuda says he announces a lost item because if you say that he announces a garment, we are concerned about a dishonest person [who, knowing that a garment was lost, might try to make a claim. Rashi gives the scenario: the dishonest person knows that his neighbor had an inscribed Rolex watch, and that the neighbor was bemoaning the loss of his watch. The dishonest man then runs to the nearest synagogue, identifies the inscription, and takes the watch]. Rav Nachman says he announces a garment; we are not concerned about dishonest people, for if so, there would be no end [i.e., we might decide not to make _any_ announcement].
We learned (in our mishna): "If one named the lost item but did not name the identifying marks, (the finder) should not give it to him." If you say that (the finder) announces a lost item, this is understandable; (the mishna) teaches us that even if he (t he claimant) said it was a garment we do not give it to him if he does not cite identifying marks. But if you say that he announces a garment, he (the finder) announces a garment and he (the claimant) says (he lost a) garment -- is it necessary (for the m ishna) to teach us that if he doesn't cite identification marks we do not give it to him? [Thus, the mishna appears to support Rav Yehuda's position that the finder simply announces that an item was found.]
Rav Safra says: Actually, he announces a garment: He (the finder) announces a garment and he (the claimant) cites identifying marks. What does (the mishna) mean by "he did not give identifying marks"? He did not give _distinctive_ identifying marks.
(The mishna said:) And a dishonest (claimant) -- even if he names identifying marks, (the finder) should not give it to him. The rabbis taught in a b'raita: Originally, anyone who lost an item would give identifying marks and take it. When dishonest peopl e became prevalent, the rabbis ruled that they would say to him (the claimant) go bring witnesses that you are not a dishonest person and take it.
This happened to the father of Rav Papa. He lost a donkey and it was found. He came before Rabba bar Rav Huna and he (Rabba bar Rav Huna) said to him (Rav Papa's father) go bring witnesses that you are not a dishonest person and take it. He brought witnes ses. He (Rabba bar Rav Huna) said to them "Do you know if he is a dishonest person?" They said to him "Yes." He (Rav Papa's father) said to them: "I am a dishonest person??!" They said to him "We meant to say that you are _not_ a dishonest person." Rabba bar Rav Huna said, "Presumably one would not bring witnesses to discredit himself" [and, on that basis, accepted the revised testimony].
[We are now at the second mishna on 28b.]