The Canons of the Council in Trullo; Often Called The Quinisext Council 80Canon LXXX.

If any bishop, or presbyter, or deacon, or any of those who are enumerated in the list of the clergy, or a layman, has no very grave necessity nor difficult business so as to keep him from church for a very long time, but being in town does not go to church on three consecutive Sundays--three weeks--if he is a cleric let him be deposed, but if a layman let him be cut off.