Exodus 12:18–20

18 You are to eat unleavened bread in the first month,r from the evening of the fourteenth day of the month until the evening of the twenty-first day. 19 Yeast must not be found in your houses for seven days. If anyone eats something leavened, that person, whether a resident alien or native of the land, must be cut off from the community of Israel. 20 Do not eat anything leavened; eat unleavened bread in all your homes.”C