The Seventh Ecumenical Council.  The Second Council of Nice 20Canon XI.

That OEconomi ought to be in the Episcopal palaces and in the Monasteries.

Since we are under obligation to guard all the divine canons, we ought by all means to maintain in its integrity that one which says oeconomi are to be in each church. If the metropolitan appoints in his Church an oeconomus, he does well; but if he does not, it is permitted to the Bishop of Constantinople by his own (idias) authority to choose an oeconomus for the Church of the Metropolitan. A like authority belongs to the metropolitans, if the Bishops who are subject to them do not wish to appoint oeconomi in their churches. The same rule is also to be observed with respect to monasteries.