Related do Keritot 1:12

One who eats chametz after midnight or chamatz which remained with him during Passover -- behold, he has violated a negative commandment, but he is not excommunicated, the words of Rabbi Yehuda. And the Sages say, whatever does not result in excommunication does not involve [the violation of] a negative commandment. One who eats an olive's-bulk of chametz on Passover [intentionally] is liable for the punishment of excommunication, but [if he did so] unintentionally, [he is liable for] a sin offering, and [if he did so] without knowing, [he is liable for] a dependent sin offering.