Numbers 9:6-7

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. 9:7 And those men said to him, “We are ceremonially defiled by the dead body of a man; why are we kept back from offering the Lord’s offering at its appointed time among the Israelites?”