Numbers 9:6

9:6 It happened that some men who were ceremonially defiled by the dead body of a man could not keep the Passover on that day, so they came before Moses and before Aaron on that day.

Numbers 9:10

9:10 “Tell the Israelites, ‘If any of you or of your posterity become ceremonially defiled by touching a dead body, or are on a journey far away, then he may observe the Passover to the Lord.