God specifies to Moses and Aaron the way the first passover should be done, and also how it should be done as a lasting annual festival. It should happen on the fourteenth of the first month, and a lamb without blemish is to be eaten, along with unleavened bread. They should put the lambs blood on their doors, so when the angel of death passes over Egypt, it knows not to go into the doors with blood on them. The Jews are to continue this practice into the future, with also a seven day Feast of Unleavened Bread.
The Jews did this, and at midnight, God struck down all the firstborn of Egypt. The Pharaoh summoned Moses and Aaron, and demanded that they left. So the Hebrews left Egypt with all their possessions, and with whatever they could get off their Egyptian masters. They left exactly 430 years after they arrived.
God makes it clear that you have to be circumcised to take part in the passover feast.
49. There shall be one law for the native and for the stranger who sojourns among you.
I figure if only some countries took that key verse seriously, then we might have a lot less problems.
There are interesting comparisons between the passover lamb and Jesus. The passover lamb is without blemish and it is the blood of that lamb which saved the people from death – like Jesus. Interestingly, God commands that no bone in the lamb is to be broken. This is often compared with Jesus, particularly in John 19:36, because none of his bones were broken, as prophesied in Psalm 34:20.
A lot of the traditions of passover come from the fact that the Jews had to rush off on the exodus shortly after the meal. They ate with sandals on and a staff in their hand. Nothing was to be left for the next day.