Final answer:
The prohibition for chametz is found in the Torah within the book of Exodus, specifically Exodus 12:15-20, and is reiterated in the book of Deuteronomy 16:3-4, in relation to the Passover festival.
Step-by-step explanation:
The prohibition for chametz, which refers to leavened grain products, is found in the Hebrew Bible within the Torah. During the festival of Passover, Jews are commanded to abstain from eating chametz as a commemoration of their ancestors' exodus from Egypt, where they did not have time to let their bread rise.
The specific prohibitions can be found primarily in the book of Exodus (Shemot), particularly Exodus 12:15-20, where the Israelites are instructed to remove chametz from their homes and to eat unleavened bread (matzah) for seven days. Additionally, the book of Deuteronomy (Devarim) reiterates this command in 16:3-4.