God said to Moses and Aaron while still in Egypt,
"This month is to be the first month of the year for you.
Address the whole community of Israel; tell them that on the tenth of this month each man is to take a lamb for his family, one lamb to a house.
If the family is too small for a lamb, then share it with a close neighbor, depending on the number of persons involved. Be mindful of how much each person will eat.
Your lamb must be a healthy male, one year old; you can select it from either the sheep or the goats.
Keep it penned until the fourteenth day of this month and then slaughter it - the entire community of Israel will do this - at dusk.