On that same night, the 15th of the Hebrew month of Nisan, the tenth and final plague, the killing of the firstborns had taken hold across Egypt. Before it began, Moses commanded the Jewish people to sacrifice a Pascal lamb and mark their doorposts with its blood. The fulfillment of this commandment protected them from the plague which passed over their households. Before they departed the next morning, the Jews baked bread, but it had no time to rise as they were hurrying to leave Egypt, meaning the bread ended up unleavened. And these are the origins of the custom of not eating leavened foods on Passover. And what did they eat you may ask? Matzo of course!