Numbers 9:6, 10

And there were certain men who were unclean through touching a dead body, so that they could not keep the Passover on that day, and they came before Moses and Aaron on that day.

“Speak to the people of Israel, saying, If any one of you or of your descendants is unclean through touching a dead body, or is on a long journey, he shall still keep the Passover to the LORD.