Exodus 12:14
And this day will be a memorial for you, and you are to celebrate it as a feast to the LORD, as a lasting ordinance for the generations to come.

Numbers 9:2
"The Israelites are to observe the Passover at its appointed time.

Deuteronomy 16:2
You are to offer to the LORD your God the Passover sacrifice from the herd or flock in the place where the LORD will choose as a dwelling for His Name.

2 Chronicles 35:1
Then Josiah celebrated the Passover to the LORD in Jerusalem, and the Passover lamb was slaughtered on the fourteenth day of the first month.

2 Chronicles 35:18
No such Passover had been observed in Israel since the days of Samuel the prophet. None of the kings of Israel ever observed a Passover like the one that Josiah observed with the priests, the Levites, all Judah, the Israelites who were present, and the people of Jerusalem.