Numbers 9:1-3

1And Jehovah spoke to Moses in the wilderness of Sinai, in the first month of the second year after their departure from the land of Egypt, saying,

2Let the children of Israel also hold the passover at its set time;

3on the fourteenth day in this month between the two evenings, ye shall hold it at its set time; according to all the rites of it, and according to all the ordinances thereof shall ye hold it.