Deuteronomy 16:1-4

Celebrate the Passover of the LORD your God during the month of Abib, because it was during Abib that he brought you out of Egypt at night. As the sacrifice for the Passover to the LORD your God, offer an animal from your flock or herd at the place the LORD will choose to be worshiped. Do not eat it with bread made with yeast. But for seven days eat bread made without yeast, the bread of suffering, because you left Egypt in a hurry. So all your life you will remember the time you left Egypt. There must be no yeast anywhere in your land for seven days. Offer the sacrifice on the evening of the first day, and eat all the meat before morning; do not leave it overnight.