Exodus 12:15

Seven days shall ye eat unleavened bread - This has been considered as a distinct ordinance, and not essentially connected with the passover. The passover was to be observed on the fourteenth day of the first month; the feast of unleavened bread began on the fifteenth and lasted seven days, the first and last of which were holy convocations.

That soul shall be cut off - There are thirty-six places in which this excision or cutting off is threatened against the Jews for neglect of some particular duty; and what is implied in the thing itself is not well known. Some think it means a violent death, some a premature death, and some an eternal death. It is very likely that it means no more than a separation from the rights and privileges of an Israelite; so that after this excision the person was considered as a mere stranger, who had neither lot nor part in Israel, nor any right to the blessings of the covenant. This is probably what St. Paul means, Romans 9:3 . But we naturally suppose this punishment was not inflicted but on those who had showed a marked and obstinate contempt for the Divine authority. This punishment appears to have been nearly the same with excommunication among the Christians; and from this general notion of the cutting off, the Christian excommunication seems to have been borrowed.