On Prayer by Tertullian
Chapter XV.--Of Putting Off Cloaks.
But since we have touched on one special point of empty observance, it will not be irksome to set our brand likewise on the other points against which the reproach of vanity may deservedly be laid; if, that is, they are observed without the authority of any precept either of the Lord, or else of the apostles. For matters of this kind belong not to religion, but to superstition, being studied, and forced, and of curious rather than rational ceremony; deserving of restraint, at all events, even on this ground, that they put us on a level with Gentiles. As, e.g., it is the custom of some to make prayer with cloaks doffed, for so do the nations approach their idols; which practice, of course, were its observance becoming, the apostles, who teach concerning the garb of prayer, would have comprehended in their instructions, unless any think that is was in prayer that Paul had left his cloak with Carpus! God, forsooth, would not hear cloaked suppliants, who plainly heard the three saints in the Babylonian king's furnace praying in their trousers and turbans.