One passage comes to mind for Gregory the Theologian, though this may not be what you (or the people you were reading) were thinking of...
"Next, on what subjects and to what extent may we philosophize? On matters within our reach, and to such an extent as the mental power and grasp of our audience may extend. No further, lest, as excessively loud sounds injure the hearing, or excess of food the body, or, if you will, as excessive burdens beyond the strength injure those who bear them, or excessive rains the earth; so these too, being pressed down and overweighted by the stiffness, if I may use the expression, of the arguments should suffer loss even in respect of the strength they originally possessed.
Now, I am not saying that it is not needful to remember God at all times;...I must not be misunderstood, or I shall be having these nimble and quick people down upon me again. For we ought to think of God even more often than we draw our breath; and if the expression is permissible, we ought to do nothing else. Yea, I am one of those who entirely approve that Word which bids us meditate day and night, and tell at eventide and morning and noon day, and praise the Lord at every time; or, to use Moses' words, whether a man lie down, or rise up, or walk by the way, or whatever else he be doing--and by this recollection we are to be moulded to purity. So that it is not the continual remembrance of God that I would hinder, but only the talking about God; nor even that as in itself wrong, but only when seasonable; nor all teaching, but only want of moderation." - Oration 27, 4-5
The only reference for Evagrius I could find was the following, which I found in an online copy of The Orthodox Church
by Bp. Kallistos:
"Theology, mysticism, spirituality, moral rules, worship, art: these things must not be kept in separate compartments. Doctrine cannot be understood unless it is prayed: a theologian, said Evagrius, is one who knows how to pray, and he who prays in spirit and in truth is by that very act a theologian (On Prayer, 60 (P. G. 79, 1180B))."