Bitul Chametz in Rambam - When Does Bitul Take Effect

Full Summary

This advanced shiur delves deeply into the Rambam (רמב"ם)'s intricate understanding of bitul chametz and its relationship to the biblical prohibitions of bal yeira and bal yimatzei. Rabbi Zweig begins by examining the Rambam's position in Hilchos Chametz uMatzah that chametz yidua (known chametz) cannot be nullified and must be destroyed, while chametz ein yidua (unknown chametz) can be nullified. This creates a fundamental difficulty with the Gemara (גמרא)'s statement that when one finds chametz during bedika, one should nullify it - how can one nullify chametz yidua? The shiur explores the Kesef Mishneh's interpretation and the broader question of when the mitzvah (מצוה) of tashbisu (destroying chametz) applies. Rabbi Zweig suggests that according to the Rambam, there may be a distinction between fulfilling tashbisu and avoiding the prohibitions of bal yeira/bal yimatzei - bitul might not fulfill tashbisu on chametz yidua but could still prevent violation of bal yeira/bal yimatzei. A major chiddush emerges from the Rambam's understanding: if one properly performed bedika and bitul, they are not in violation of bal yeira/bal yimatzei even if chametz is later found in their home on Pesach (פסח). The Torah (תורה) only considers chametz to be 'in one's possession' for purposes of these prohibitions when one failed to properly dispose of known chametz. This revolutionary interpretation means that chametz found after proper bedika and bitul does not create liability. The analysis extends to the timing of bitul itself. Rabbi Zweig proposes that according to the Rambam, when one performs bitul at night after bedika, the nullification doesn't take effect immediately but rather becomes effective in the morning before the prohibition begins. This explains why the Gemara requires bitul to be done at night rather than in the morning - it's a precautionary measure for chametz one might have forgotten about. The shiur concludes with a fundamental reframing of the entire sugya: the Gemara's discussion isn't primarily about the mitzvah of tashbisu but about preventing violations of bal yeira/bal yimatzei. The case involves someone who knew about chametz, planned to burn it, but forgot - this person is liable for bal yeira/bal yimatzei from the time the prohibition begins until the chametz is found. The solution is preventative bitul performed the night before.