"This month shall be your beginning of months; it shall be the first month of the year to you. Speak to all the congregation of Israel, saying, 'On the tenth of this month every man shall take for himself a lamb, according to the house of his father, a lamb for a household. And if the household is too small for the lamb, let him and his neighbor next to his house take it according to the number of persons; according to each man's need you shall make your count for the lamb. Your lamb shall be without blemish, a male of the first year. You may take it from the sheep or from the goats. Now you shall keep it until the fourteenth day of the same month. Then the whole congregation of Israel shall kill it at twilight. And they shall take some of the blood and put it on the two doorposts and on the lintel of the houses where they eat it. Then they shall eat the flesh on that night; roasted in fire, with unleavened bread and with bitter herbs they shall eat it. Do not eat it raw, nor boiled at all with water, but roasted in fire--its head with its legs and its entrails. You shall let none of it remain until morning, and what remains of it until morning you shall burn with fire. And thus you shall eat it: with a belt on your waist, your sandals on your feet, and your staff in your hand. So you shall eat it in haste. It is the LORD's Passover" (Exo. 12:1-11).
God has made them a great nation and is giving them their own calendar. God wanted them to be both free and distinct from Egypt and its influences; He wanted them to be consecrated to Him. The Passover would help make both a reality. They were to eat it in a hurry and be fully clothed because they would be journeying soon and needed to be ready. This was not to be a large gathering but a family affair.
God continued - "For I will pass through the land of Egypt on that night, and will strike all the firstborn in the land of Egypt, both man and beast; and against all the gods of Egypt I will execute judgment: I am the LORD. Now the blood shall be a sign for you on the houses where you are. And when I see the blood, I will pass over you; and the plague shall not be on you to destroy you when I strike the land of Egypt. So this day shall be to you a memorial; and you shall keep it as a feast to the LORD throughout your generations. You shall keep it as a feast by an everlasting ordinance" (12:12-14). This plague would be the final blow against the Egyptian gods, exposing their impotence.
Lambs were selected by the Israelites and then slain at the appropriate time. The doorposts and lintels were marked with blood. When the LORD passed through the land, He would slay the Egyptian firstborn who were not protected by the blood, but no Israelite would perish--God would pass over them. Although the death of the firstborn was a one-time occurrence, the Passover and Feast of Unleavened Bread were to be remembered every year. This annual reminder would be important so that the nation would not forget where it came from and what it was delivered from--slavery and death. Additionally, it would provide a perfect opportunity to give a history lesson to the children. Each generation needed to be taught what God had done for them so they would not forsake Him (and so it is even today). God is adamant that none of the people eat any leaven (i.e., yeast) during the Passover and Feast of Unleavened Bread. Leaven is often used in Scripture as a natural symbol of impurity or moral corruption. God wanted them to be separate and pure. Furthermore, they are going to be leaving Egypt very quickly and wouldn't have had time for leavened dough to rise. They were also to eat bitter herbs with the meat and bread, likely symbolizing the bitterness of life they had experienced in Egypt.
There are some wonderful comparisons that can be made between the Passover lamb and Jesus as the Lamb of God (cf. I Cor. 5:7). These similarities are not by accident but by God's design. Both the Passover lamb and Jesus were chosen by the f(F)ather and both were inspected for a period of time to ensure there were no blemishes. Both were slain at twilight and neither had any bones broken. Both had the power to save in their blood, when it was properly applied. Both would have a memorial which was to be kept and taught faithfully. The interested student is encouraged to consider these points of comparison explained in detail in our archived lesson from 02/11/06.