Exodus 12:20-22

New Century Version

²⁰ During this feast you must not eat anything made with yeast. You must eat only bread made without yeast wherever you live.”

²¹ Then Moses called all the elders of Israel together and told them, “Get the animals for your families and kill the lamb for the Passover. ²² Take a branch of the hyssop plant, dip it into the bowl filled with blood, and then wipe the blood on the sides and tops of the doorframes. No one may leave that house until morning.