Numbers 9:6-11

6And there were certain men, who were unclean by reason of the dead body of a man, so that they could not keep the passover on that day: and they came before Moses and before Aaron on that day: 7and those men said unto him, We are unclean by reason of the dead body of a man: wherefore are we kept back, that we may not offer the oblation of Jehovah in its appointed season among the children of Israel? 8And Moses said unto them, Stay ye, that I may hear what Jehovah will command concerning you.

9And Jehovah spake unto Moses, saying, 10Speak unto the children of Israel, saying, If any man of you or of your generations shall be unclean by reason of a dead body, or be on a journey afar off, yet he shall keep the passover unto Jehovah. 11In the second month on the fourteenth day at even they shall keep it; they shall eat it with unleavened bread and bitter herbs: