There are two main approaches among the early commentators regarding the definition of the mitzvah of getting rid of chametz. Onkelos and Rashi interpret it as nullifying in one's heart, similar to the explanation given by the Ramban, who describes it as considering the chametz like dust and ashes. The Rambam also uses similar language, saying one should think of it as dust and believe in his heart that he has no chametz at all. However, according to the Tosafot, nullifying chametz is seen as a legal concept of relinquishing ownership and removal from one's possession. In this case, the chametz is subject to the prohibition of "it shall not be seen or found," and the mitzvah of getting rid of chametz is carried out practically. According to Rabbi Yehuda, this is done through burning, while the Sages allow for other methods such as crumbling and scattering, throwing to the wind, or casting into the sea.