'Passover' in the Bible
"The Israelites are to observe the Passover at its appointed time.
And they observed the Passover on the fourteenth day of the first month at twilight in the wilderness of Sinai; in accordance with all that the Lord had commanded Moses, so the Israelites did.
It happened that some men who were ceremonially defiled by the dead body of a man could not keep the Passover on that day, so they came before Moses and before Aaron on that day.
"Tell the Israelites, 'If any of you or of your posterity become ceremonially defiled by touching a dead body, or are on a journey far away, then he may observe the Passover to the Lord.
They must not leave any of it until morning, nor break any of its bones; they must observe it in accordance with every statute of the Passover.
But the man who is ceremonially clean, and was not on a journey, and fails to keep the Passover, that person must be cut off from his people. Because he did not bring the Lord's offering at its appointed time, that man must bear his sin.
If a resident foreigner lives among you and wants to keep the Passover to the Lord, he must do so according to the statute of the Passover, and according to its custom. You must have the same statute for the resident foreigner and for the one who was born in the land.'"
"'On the fourteenth day of the first month is the Lord's Passover.
They departed from Rameses in the first month, on the fifteenth day of the first month; on the day after the Passover the Israelites went out defiantly in plain sight of all the Egyptians.