The Jewish feast of Passover celebrates the time when God protected His people, Israel, from the plague that came upon the Egyptians, to kill their first-born sons. This plague was sent because Pharoah repeatedly refused to release the Israelites from captivity. God told Moses to tell His people to go into their homes, and the head of the household was to take the blood of a slain lamb and put the blood on the top and sides of their doors.