Numbers 9:6-10

Now there were certain men who were defiled by a human corpse, so that they could not keep the Passover on that day; and they came before Moses and Aaron that day. And those men said to him, “We became defiled by a human corpse. Why are we kept from presenting the offering of the LORD at its appointed time among the children of Israel?” And Moses said to them, “Stand still, that I may hear what the LORD will command concerning you.” Then the LORD spoke to Moses, saying, “Speak to the children of Israel, saying: ‘If anyone of you or your posterity is unclean because of a corpse, or is far away on a journey, he may still keep the LORD’s Passover.