Numbers 9:6, 10

But there were some men who were unclean because of the dead person, so that they could not observe Passover on that day; so they came before Moses and Aaron on that day.

“Speak to the sons of Israel, saying, ‘If any one of you or of your generations becomes unclean because of a dead person, or is on a distant journey, he may, however, observe the Passover to the LORD.