Exodus 12:5-13

Your lamb shall be without blemish, a male a year old: ye shall take it from the sheep, or from the goats: and ye shall keep it until the fourteenth day of the same month; and the whole assembly of the congregation of Israel shall kill it at even. And they shall take of the blood, and put it on the two side-posts and on the lintel, upon the houses wherein they shall eat it. And they shall eat the flesh in that night, roast with fire, and unleavened bread; with bitter herbs they shall eat it. Eat not of it raw, nor boiled at all with water, but roast with fire; its head with its legs and with the inwards thereof. And ye shall let nothing of it remain until the morning; but that which remaineth of it until the morning ye shall burn with fire. And thus shall ye eat it: with your loins girded, your shoes on your feet, and your staff in your hand; and ye shall eat it in haste: it is Jehovah’s passover. For I will go through the land of Egypt in that 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 judgments: I am Jehovah. 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 there shall no plague be upon you to destroy you, when I smite the land of Egypt.