An example of this disagreement is presented by the Gemara:
Said Rabba bar Avuh in the name of Rav: The case where one ate a piece of fat about which there was a doubt whether it was ḥelev (forbidden fat) or permitted fat forms the subject of a dispute between Rabbi Eliezer and the Sages. But why present the case that he ate it? Even if he did not eat it he may offer such a guilt offering according to Rabbi Eliezer, as we have learned: Rabbi Eliezer says, A man may volunteer to bring a provisional guilt offering every day.
Said Rav Ashi: Rabbi Eliezer follows here the view of Bava ben Buta,of whom we have learned: But they said to him, Wait until you enter a situation of potential uncertainty.
Rashi explains that the Gemara is referring to the Mishna later on in Massekhet Karetot (daf 25a). In that Mishna there are three approaches to the law of asham taluy.
1. According to Rabbi Eliezer, an asham taluy can be donated at any time, even if there is no reason to think that the person sinned.
2. Bava ben Buta suggests that an asham taluy cannot be donated unless there is a possibility that the person sinned.
3. The Sages rule that an asham taluy is brought only in the event that the person believes that he may have transgressed a sin for which he would be liable to receive the punishment of karet.
As we learned on yesterday’s daf there is a disagreement regarding the question about when an asham taluy – a provisional guilt offering – is brought. The Sages rule that this sacrifice is only brought when a person ate ḥatikha aḥat mi-shtei ḥatikhot – “a single piece out of two,” where one was permitted and one was forbidden. If, however, there is doubt as to whether the piece was forbidden at all – it was a case of ḥatikha aḥat, “a single piece” – then an asham taluy would not be brought. Rabbi Eliezer disagrees with this analysis and rules that someone who ate a single piece whose status was questionable is obligated to bring an asham taluy.