Exodus 12:1 And the Lord spake unto Moses and Aaron in the land of Egypt saying, 3 Speak ye unto all the congregation of Israel, saying, In the tenth day of this month they shall take to them every man a lamb, according to the house of their fathers, a lamb for an house.
[Patriarchs & Prophets pp 274] Before the execution of this sentence the Lord through Moses gave direction to the children of Israel concerning their departure from Egypt, and especially for their preservation from the coming judgment. Each family, alone or in connection with others, was to slay a lamb or a kid “without blemish,” and with a bunch of hyssop sprinkle its blood on “the two side posts and on the upper doorpost” of the house, that the destroying angel, coming at midnight, might not enter that dwelling. They were to eat the flesh roasted, with unleavened bread and bitter herbs, at night, as Moses said, “with your loins girded, your shoes on your feet, and your staff in your hand; and ye shall eat it in haste: it is the Lord's Passover.”
The Lord declared: “I will pass through the land of Egypt this night, and will smite all the first-born in the land of Egypt, both man and beast; and against all the gods of Egypt I will execute judgment.... And the blood shall be to you for a token upon the houses where ye are: and when I see the blood, I will pass over you, and the plague shall not be upon you to destroy you, when I smite the land of Egypt.” In commemoration of this great deliverance a feast was to be observed yearly by the people of Israel in all future generations. “This day shall be unto you for a memorial; and ye shall keep it a feast to the Lord throughout your generations: ye shall keep it a feast by an ordinance forever.”
As they should keep the feast in future years, they were to repeat to their children the story of this great deliverance, as Moses bade them: “Ye shall say, It is the sacrifice of the Lord's Passover, who passed over the houses of the children of Israel in Egypt, when He smote the Egyptians, and delivered our houses.” Furthermore, the first-born of both man and beast were to be the Lord's, to be bought back only by a ransom, in acknowledgment that when the first-born in Egypt perished, that of Israel, though graciously preserved, had been justly exposed to the same doom but for the atoning sacrifice.
Exodus 13:1 And the Lord spake unto Moses, saying, 2 Sanctify unto me all the firstborn, whatsoever openeth the womb among the children of Israel, both of man and of beast: it is mine.
May The Lord add His blessing to the study of His word. God bless!