'On that Day' in the Bible

The priest is to offer one as a sin offering and the other as a burnt offering to make atonement on behalf of the Nazirite, since he sinned because of the corpse. On that day he must consecrate his head again.

But there were some men who were unclean because of a human corpse, so they could not observe the Passover on that day. These men came before Moses and Aaron the same day