The Epistle of Ignatius of Antioch to the Philadelphians
Ignatius, who is also called Theophorus, to the Church of God the Father, and our Lord Jesus Christ, which is at Philadelphia, in Asia, which has obtained mercy, and is established in the harmony of God, and rejoices unceasingly in the passion of our Lord, and is filled with all mercy through his resurrection; which I salute in the blood of Jesus Christ, who is our eternal and enduring joy, especially if [men] are in unity with the bishop, the presbyters, and the deacons, who have been appointed according to the mind of Jesus Christ, whom He has established in security, after His own will, and by His Holy Spirit.
Chapter 1. Praise of the bishop
Which bishop, I know, obtained the ministry which pertains to the common [good], not of himself, neither by men, Galatians 1:1 nor through vainglory, but by the love of God the Father, and the Lord Jesus Christ; at whose meekness I am struck with admiration, and who by his silence is able to accomplish more than those who vainly talk. For he is in harmony with the commandments [of God], even as the harp is with its strings. Wherefore my soul declares his mind towards God a happy one, knowing it to be virtuous and perfect, and that his stability as well as freedom from all anger is after the example of the infinite meekness of the living God.
Chapter 2. Maintain union with the bishop
Wherefore, as children of light and truth, flee from division and wicked doctrines; but where the shepherd is, there follow as sheep. For there are many wolves that appear worthy of credit, who, by means of a pernicious pleasure, carry captive 2 Timothy 3:6 those that are running towards God; but in your unity they shall have no place.
Chapter 3. Avoid schismatics
Keep yourselves from those evil plants which Jesus Christ does not tend, because they are not the planting of the Father. Not that I have found any division among you, but exceeding purity. For as many as are of God and of Jesus Christ are also with the bishop. And as many as shall, in the exercise of repentance, return into the unity of the Church, these, too, shall belong to God, that they may live according to Jesus Christ. Do not err, my brethren. If any man follows him that makes a schism in the Church, he shall not inherit the kingdom of God. If any one walks according to a strange opinion, he agrees not with the passion [of Christ.].
Chapter 4. Have but one Eucharist, etc
Take heed, then, to have but one Eucharist. For there is one flesh of our Lord Jesus Christ, and one cup to [show forth ] the unity of His blood; one altar; as there is one bishop, along with the presbytery and deacons, my fellow-servants: that so, whatsoever you do, you may do it according to [the will of] God.
The Epistle of Ignatius to the Smyrnaeans
Chapter 8. Let nothing be done without the bishop
See that you all follow the bishop, even as Jesus Christ does the Father, and the presbytery as you would the apostles; and reverence the deacons, as being the institution of God. Let no man do anything connected with the Church without the bishop. Let that be deemed a proper Eucharist, which is [administered] either by the bishop, or by one to whom he has entrusted it. Wherever the bishop shall appear, there let the multitude [of the people] also be; even as, wherever Jesus Christ is, there is the Catholic Church. It is not lawful without the bishop either to baptize or to celebrate a love-feast; but whatsoever he shall approve of, that is also pleasing to God, so that everything that is done may be secure and valid.
Chapter 9. Honour the bishop
Moreover, it is in accordance with reason that we should return to soberness [of conduct], and, while yet we have opportunity, exercise repentance towards God. It is well to reverence both God and the bishop. He who honours the bishop has been honoured by God; he who does anything without the knowledge of the bishop, does [in reality] serve the devil. Let all things, then, abound to you through grace, for you are worthy. You have refreshed me in all things, and Jesus Christ [shall refresh] you. You have loved me when absent as well as when present. May God recompense you, for whose sake, while you endure all things, you shall attain unto Him.
Source: New Advent Encyclopedia