'Passover' in the Bible
“The sons of Israel are to keep the Passover at its appointed time.
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.
But there were certain men who were [ceremonially] unclean because of [touching] the dead body of a man, so they could not observe the Passover on that day; so they came before Moses and Aaron that same day.
“Say to the Israelites, ‘If any one of you or of your descendants becomes [ceremonially] unclean because of [touching] a dead body or is on a distant journey, he may, however, observe the Passover to the Lord.
They shall leave none of it until morning nor break any of its bones; in accordance with all the statutes of the Passover they shall observe it.
But the man who is [ceremonially] clean and is not on a journey, and yet does not observe the Passover, that person shall be cut off from among his people [excluding him from the atonement made for them] because he did not bring the Lord’s offering at its appointed time; that man will bear [the penalty of] his sin.
If a stranger lives among you as a resident alien and observes the Passover to the Lord, in accordance with its statutes and its ordinances, so shall he do; you shall have one statute, both for the resident alien and for the native of the land.’”
‘The Lord’s Passover shall be on the fourteenth day of the first month [of each year].
They set out from Rameses on the fifteenth day of the first month; on the day after the Passover the Israelites moved out triumphantly in the sight of all the Egyptians,