Numbers 9:5-7

King James Version

⁵ And they kept the passover on the fourteenth day of the first month at even in the wilderness of Sinai: according to all that the Lord commanded Moses, so did the children of Israel.

⁶ And there were certain men, who were defiled by the dead body of a man, that they could not keep the passover on that day: and they came before Moses and before Aaron on that day:

⁷ And those men said unto him, We are defiled by the dead body of a man: wherefore are we kept back, that we may not offer an offering of the Lord in his appointed season among the children of Israel?