..believe no teacher unless.....

—Temptation of Christ.  (Ante Nicene Vol. 8 p. 143)

“This we would have you know assuredly, that a demon has no power against a man, unless
one voluntarily submit himself to his desires. Whence even that one who is the prince of
wickedness, approached Him who, as we have said, is appointed of God King of peace, tempting
Him, and began to promise Him all the glory of the world; because he knew that when he had
offered this to others, for the sake of deceiving them, they had worshipped him. Therefore, impious as he was, and unmindful of himself, which indeed is the special peculiarity of wickedness, he presumed that he should be worshipped by Him by whom he knew that he was to be destroyed.  Therefore our Lord, confirming the worship of one God, answered him: ‘It is written, Thou shalt worship the Lord thy God, and Him only shalt thou serve.’ And he, terrified by this answer, and fearing lest the true religion of the one and true God should be restored, hastened straightway to send forth into this world false prophets, and false apostles, and false teachers, who should speak indeed in the name of Christ, but should accomplish the will of the demon.

—False Apostles.

“Wherefore observe the greatest caution, that you believe no teacher, unless he bring from Jerusalem the testimonial of James the Lord’s brother, or of whosoever may come after him.
For no one, unless he has gone up thither, and there has been approved as a fit and faithful teacher for preaching the word of Christ,—unless, I say, he brings a testimonial thence, is by any means to be received. But let neither prophet nor apostle be looked for by you at this time, besides us. For there is one true Prophet, whose words we twelve apostles preach; for He is the accepted year of God, having us apostles as His twelve months. But for what reason the world itself was made, or what diversities have occurred in it, and why our Lord, coming for its restoration, has chosen and sent us twelve apostles, shall be explained more at length at another time. Meantime He has commanded us to go forth to preach, and to invite you to the supper of the heavenly King, which the Father hath prepared for the marriage of His Son, and that we should give you wedding garments, that is, the grace of baptism; which whosoever obtains, as a spotless robe with which he is to enter to the supper of the King, ought to beware that it be not in any part of it stained with sin, and so he be rejected as unworthy and reprobate.

—Misrepresentation of Peter’s Doctrine. (Ante Nicene Vol. 8 p. 215)

In order, therefore, that the like may also happen to those among us as to these Seventy, give
the books of my preachings to our brethren, with the like mystery of initiation, that they may
indoctrinate those who wish to take part in teaching; for if it be not so done, our word of truth will
be rent into many opinions. And this I know, not as being a prophet, but as already seeing the beginning of this very evil. For some from among the Gentiles have rejected my legal preaching,
attaching themselves to certain lawless and trifling preaching of the man who is my enemy. And these things some have attempted while I am still alive, to transform my words by certain various interpretations, in order to the dissolution of the law; as though I also myself were of such a mind, but did not freely proclaim it, which God forbid!  For such a thing were to act in opposition to the law of God which was spoken by Moses, and was borne witness to by our Lord in respect of its eternal continuance; for thus he spoke: “The heavens and the earth shall pass away, but one jot or one tittle shall in no wise pass from the law.” And this He has said, that all things might come to pass. But these men, professing, I know not how, to know my mind, undertake to explain my words, which they have heard of me, more intelligently than I who spoke them, telling their catechumens that this is my meaning, which indeed I never thought of. But if, while I am still alive, they dare thus to misrepresent me, how much more will those who shall come after me dare to do so!