On Prayer by Tertullian
Chapter XVI.--Of Sitting After Prayer.
Again, for the custom which some have of sitting when prayer is ended, I perceive no reason, except that which children give. For what if that Hermas, whose writing is generally inscribed with the title The Shepherd, had, after finishing his prayer, not sat down on his bed, but done some other thing: should we maintain that also as a matter for observance? Of course not. Why, even as it is the sentence, |When I had prayed, and had sat down on my bed,| is simply put with a view to the order of the narration, not as a model of discipline. Else we shall have to pray nowhere except where there is a bed! Nay, whoever sits in a chair or on a bench, will act contrary to that writing. Further: inasmuch as the nations do the like, in sitting down after adoring their petty images; even on this account the practice deserves to be censured in us, because it is observed in the worship of idols. To this is further added the charge of irreverence, -- intelligible even to the nations themselves, if they had any sense. If, on the one hand, it is irreverent to sit under the eye, and over against the eye, of him whom you most of all revere and venerate; how much more, on the other hand, is that deed most irreligious under the eye of the living God, while the angel of prayer is still standing by unless we are upbraiding God that prayer has wearied us!