In Judaism, the rules forbidding the eating of certain foods and requiring that other foods be prepared in a specific way. These rules determine which foods can be called kosher. Most information regarding kashruth is found in the Hebrew Bible in the books of Leviticus, Deuteronomy, Genesis, and Exodus. Jews observing kashruth may eat only fish with scales and fins and animals that chew the cud and have cloven feet; shellfish and pork are thus forbidden. Animals and birds must be slaughtered according to ritual and with prayer. Meat and dairy products must be strictly separated; they may not be eaten at the same meal or from the same set of dishes. No restrictions apply to the use of fruits and vegetables. During Passover, bread and other baked goods must be made without leaven.