Exodus 12:3-7

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 their fathers’ houses, a lamb for a household: and if the household be too little for a lamb, then shall he and his neighbor next unto his house take one according to the number of the souls; according to every man’s eating ye shall make your count for the lamb. 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.