[Barnabas XIV:3-4, II Hermas Command VI:7-18]
Barnabas XIV: Now let us go on to the other kind of knowledge and doctrine. There are two ways of doctrine and power; the one of light, the other of darkness.  There is a great deal of difference between these two ways: for over one are appointed the angels of God, the leaders of the way of light; over the other, the angels of Satan. And the one is the Lord from everlasting to everlasting; the other is the prince of the time of unrighteousness.
II Hermas Command VI:7-18 "Hear now," saith he, "concerning faith. There are two angels with a man, one of righteousness and one of wickedness."
"How then, Sir," say I, "shall I know their workings, seeing that both angels dwell with me?"
"Hear," saith he, "and understand their workings. The angel of righteousness is delicate and bashful and gentle and tranquil. When then this one enters into thy heart, forthwith he speaketh with thee of righteousness, of purity, of holiness, and of contentment, of every righteous deed and of every glorious virtue. When all these things enter into thy heart, know that the angel of righteousness is with thee. [These then are the works of the angel of righteousness.] Trust him therefore and his works.
Now see the works of the angel of wickedness also. First of all, he is quick tempered and bitter and senseless, and his works are evil, overthrowing the servants of God. Whenever then he entereth into thy heart, know him by his works."
"How I shall discern him, Sir," I reply, "I know not." Listen," saith he. "When a fit of angry temper or bitterness comes upon thee, know that he is in thee. Then the desire of much business and the costliness of many viands and drinking bouts and of many drunken fits and of various luxuries which are unseemly, and the desire of women, and avarice, and haughtiness and boastfulness, and whatsoever things are akin and like to these--when then these things enter into thy heart, know that the angel of wickedness is with thee.
Do thou therefore, recognizing his works, stand aloof from him, and trust him in nothing, for his works are evil and inexpedient for the servants of God. Here then thou hast the workings of both the angels. Understand them, and trust the angel of righteousness.
But from the angel of wickedness stand aloof, for his teaching is evil in every matter; for though one be a man of faith, and the desire of this angel enter into his heart, that man, or that woman, must commit some sin.
And if again a man or a woman be exceedingly wicked, and the works of the angel of righteousness come into that man's heart, he must of necessity do something good.
Thou seest then," saith he, "that it is good to follow the angel of righteousness, and to bid farewell to the angel of wickedness.
This commandment declareth what concerneth faith, that thou mayest trust the works of the angel of righteousness, and doing them mayest live unto God. But believe that the works of the angel of wickedness are difficult; so by not doing them thou shalt live unto God."