Numbers 9:9-12

9Then the Lord spoke to Moses, saying,

10“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.

11On the fourteenth day of the second month [thirty days later] at twilight, they shall observe it; they shall eat it with unleavened bread and bitter herbs.

12They 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.