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.
Numbers 9:6
Surrounding context
9:5 And they kept the Passover on the fourteenth day of the first month, at twilight, in the Wilderness of Sinai; according to all that the LORD commanded Moses, so the children of Israel did.
9:6 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.
9:7 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?"