Read Exodus 12:1-20)
The Lord makes all things new to those whom he delivers from the bondage of Satan, and takes to himself to be his people. The time when he does this is to them the beginning of a new life. God appointed that, on the night wherein they were to go out of Egypt, each family should kill a lamb, or that two or three families, if small, should kill one lamb. This lamb was to be eaten in the manner here directed, and the blood to be sprinkled on the door-posts, to mark the houses of the Israelites from those of the Egyptians. The angel of the Lord, when destroying the first-born of the Egyptians, would pass over the houses marked by the blood of the lamb: hence the name of this holy feast or ordinance. The passover was to be kept every year, both as a remembrance of Israel’s preservation and deliverance out of Egypt, and as a remarkable type of Christ. Their safety and deliverance were not a reward of their own righteousness, but the gift of mercy. Of this they were reminded, and by this ordinance they were taught, that all blessings came to them through the shedding and sprinkling of blood. Observe, 1. The paschal lamb was typical. Christ is our passover, 1 Corinthians 5:7,8. Having received Christ Jesus the Lord, we must continually delight ourselves in Christ Jesus. No manner of work must be done, that is, no care admitted and indulged, which does not agree with, or would lessen this holy joy. The Jews were very strict as to the passover, so that no leaven should be found in their houses. It must be a feast kept in charity, without the leaven of malice; and in sincerity, without the leaven of hypocrisy. It was by an ordinance for ever; so long as we live we must continue feeding upon Christ, rejoicing in him always, with thankful mention of the great things he has done for us.
For a more detailed explanation select the link below.
13 The blood shall be to you for a token on the houses where you are. When I see the blood, I will pass over you, and no plague will be on you to destroy you when I strike the land of Egypt.