Exodus 12:8, 18, 34, 39

That same night they must roast the meat over a fire and eat it along with bitter salad greens and bread made without yeast.

The bread you eat must be made without yeast from the evening of the fourteenth day of the first month until the evening of the twenty-first day of that month.

The Israelites took their bread dough before yeast was added. They wrapped their kneading boards in their cloaks and carried them on their shoulders.

For bread they baked flat cakes from the dough without yeast they had brought from Egypt. It was made without yeast because the people were driven out of Egypt in such a hurry that they had no time to prepare the bread or other food.