Numbers 9:9-11

9Then the Lord spoke to Moses, saying,

10“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.

11On the fourteenth day of the second month, at twilight, they may keep it. They shall eat it with unleavened bread and bitter herbs.