Didache 15.
Appoint therefore to yourselves bishops and deacons worthy of the Lord, men who are meek and not lovers of money, and true and approved ; for unto you they also perform the service of the prophets and teachers.
1 Clement 42
So preaching everywhere in country and town, [the Apostles] appointed their first-fruits, when they had approved them by the Spirit, to be bishops and deacons unto them that should believe. And this they did in no new fashion; for indeed it had been written concerning bishops and deacons from very ancient times; for thus saith the scripture in a certain place, I will appoint their bishops in righteousness and their deacons in faith.
Polycarp, Epistle 5.2
In like manner deacons should be blameless in the presence of his righteousness, as deacons of God and Christ and not of men; not calumniators, not double-tongued, not lovers of money, temperate in all things, compassionate, diligent, walking according to the truth of the Lord who became a deacon of all.
Hermas, Similitudes 9.26.2
They [in the vision] that have the spots are the deacons that exercised their office ill, and plundered the livelihood of widows and orphans, and made gain for themselves from the ministrations which they had received to perform.
REFERENCES IN 2ND-3RD CENTURY WRITERS
Justin, 1 Apol. 67 [describing their Sunday worship] And there is a distribution [of the bread and wine] to each,...and to those who are absent a portion is sent by the deacons.
Hippolytus, Refutation of all Heresies 9.7 About the time of this man [Callistus], bishops, priests and deacons who had been twice married, and thrice married, began to be allowed to retain their place among the clergy.
Eusebius, H.E. 7.11.24 [quoting Dionysius of Corinth, ca. 170]: The presbyters...concealed themselves in the city,...but the deacons, Faustus, Eusebius and Chaeremon, have survived those hwo died in the pestilence. Eusebius is one whom God has strengthened and endowed fromt he first to fulfill energetically the ministrations for the imprisoned confessors, and to attend to the dangerous task of preparing for burial the bodies of the pefected and blessed martyrs.
Cyprian, Ep. 64.2
But deacons ought to remember that the Lord chose apostles, that is bishops and overseers; while apostles appointed for themselves deacons after the ascent of the Lord into heaven, as minsters of their episcopacy and of the church.
REFERENCES IN 4TH CENTURY WRITERS
Chrysostom, Homily on 1 Tim 3:8ff
Some have thought that this [1 Tim 3:11] is said of women generally, but it is not so, for why should he introduce anything about women to interfere with his subject? He is speaking of those who hold the rank of deaconesses.
Jerome, Ep. 125.15
Each church has a single bishop, a single archpresbyter, a single archdeacon; and every ecclesiastical order is subjected to its own rulers.
Jerome, Ep. 146
Bishops, presbyters and deacons occupy in the church the same positions as those which were occupied by Aaron, his sons, and the Levites in the temple.
Pseudo-Clement, Epistle to James 12
Let the deacons of the church move about intelligently and act as eyes of the bishop, carefully inquiring into the actions of every church member....let them find out those who are sick in the flesh, and bring such to the notice of the main body who know nothing of them, that they may visit them and supply their wants, and the president may judge fit.
REFERENCES IN THE APOSTOLIC CONSTITUTIONS (dating from the 4th century but
incorporating earlier material)
2.25. These [bishops] are your high priests, as the presbyters are your priests, and your present deacons instead of your Levites; as are also your readers, your singers, your porters, your deasconesses, your widows, your virgins, and your orphans: but he who is above all these is the High Priest.
2.26. For let the bishop preside over you as one honoured with the authority of God.... But let the deacon minister to him, as Christ does to his Father; and let him serve him unblameably in all things, as Christ does nothing of himself, but does always those things that please his Father. Let also the deaconesses be honoured by you in the place of the Holy Ghost, and not do or say anything without the deacon; as neither does the comforter say or do anything of himself, but gives glory to Christ by waiting for his pleasure. And as we cannot believe on Christ without the teaching of the Spirit, so let not any woman address herself to the deacon or bishop without the deaconess.
2.28. If any determine to invite elder women to an entertainment of love, or a feast, as our Saviour calls it, let them most frequently send to such a one whom the deacons know to be in distress.
2.28. Let [the laity] not on all occasions trouble their governor, but let them signify their desires by those who minister to him, that is, by the deacons, with whom they may be more free. For neither may we address ourselves to Almighty God, but only by Christ.
2.30. For now the deacon is to you Aaron, and the bishop Moses. If therefore Moses was called a god by the Lord, let the bishop be honored among you as a god, and the deacon as his prophet.
2.32. If therefore, O deacon, thou knowest anyone to be in destress, put the bishop in mind of him, and so give to him
2.44. Let the deacon refer all things to the bishop, as Christ does to his Father. But let him order such things as he is able by himself, receiving power from the bishop, as the Lord did from His Father the power of creation and of providence. But the weighty matters let the bishop judge; but let the deacon be the bishop's ear, and eye, and mouth, and heart, and soul, that the bishop may not be distracted with many cares, but with such only as are more considerable, as Jethro did appoint for Moses, and his counsel was received.
2.57. While the Gospel is read, let all the presbyters and deacons, and all the people, stand up in great silence;...Let the deaconesses also stand at [the entries] of the women, like shipman.
2.57. But if any one be found sitting out of his place, let him be rebuked by the deacon, as a manager of a foreship, and be removed into the place proper for him. ... Let the deacon be the disposer of the places, that every one of those that comes in may go to his proper place, and may not sit at the entrance. In like manner, let th edeacon oversee the people, that nobody may whisper, nor slumber, nor laugh, nor nod; for all ought in the church to stand wisely, and soberly, and attentively, having their attention fixed upon the word of the Lord.
2.57. As to the deacons, after the prayer is over, let some of them attend upon the oblation of the Eucharist, ministering to the lord's body with fear. Let others of them watch the multitude,a nd keep them silent. But let that deacon who is at the high prienst's hand say to the peope, Let no one have any quarrel against another; let no one come in hypocrisy.
3.15. Let not therefore either a bishop, or a presbyter, or a deacon, defile his tongue with calumny.
3.15. O bishop, do thou ordain thy fellow-workers, the labourers for life and for righteousness, such deacons as are pleasing to God, such whom thou provest to be worthy among all the people, and such as shall be ready for the necessities of their ministration. Ordain also a deaconess who is faithful and holy, for the ministrations towards women. For sometimes he cannot send a deacon, who is a man, to the women, on account of unbelievers. Thou shalt therefore send a woman, a deaconess, on account of the imaginations of the bad. For we stand in need of a woman, a deaconess, for many necessities; and first in the baptism of women, the deacon shall anoint only their forehead with the holy oil, and after him the deaconess shall anoint them: for there is no necessity that the women should be seen by the men...
3.19. Let hte deacons be in all things unspotted, as the bishop himself is to be, only more active; in number according to the largeness of the church, that they many minister to the infirm as workmen that are not ashamed. And let the deaconess be diligent in taking care of the women; but both of them ready to carry messages, to travel about, to minister, and to serve. ... It is your duty who are deacons to visit all those who stand in need of visitation.
3.20. The presbyter is only to teach, to offer, to baptize, to bless the people, and the deacon is to minister to the bishop, and to the presbyters, that is, to do the office of a ministering deacon, but not to meddle with the other offices.
6.17. A bishop, a presbyter and a deacon, when they are constituted, must be but once married, whether their wives be alive or whether they be dead; and that it is not lawful for them, if they are unmarried when they are ordained, to be married afterwards...
8.17-21. [Prayers to be made by the bishop when he ordains deasons, deaconess, and sub-deacons.]
8.28. A deacon does no bless, does not give the blessing, but receives it from the bishop and presbyter: he does not baptize, he does not offer; but when a bishop or presbyter has offered, he distributes to the people, not as a priest, but as one that ministers to the priests. ... A deaconess does not bless, nor perform anything belonging to the office of presbyters or deacons, but only is to keep the doors, and to minister to the presbyters in the baptizing of women, on account of decency.
Ignatius, Magnesians 6.1 250 AD
Be ye zealous to do all things in godly concord, the bishop presiding after the likeness of God and the presbyters after the likeness of the council of the Apostles, with the deacons also, who are most dear to me, having been entrusted with the diaconate of Jesus Christ.
Ignatius, Trallians 3.1 250 AD
Let all men respect the deacons as Jesus Christ, even as they should respect the bishop as being a type of the Father and the presbyters as the council of God and as the college of Apostles. Apart from these there is not even the name of a church.
Ignatius, Philadelphians 10 250 AD
Seeing...that the church which is in Antioch of Syria hath peace, it is becoming for you, as a church of God, to appoint a deacon to go thither as God's ambassador, that he may congratulate them when they are assembled together, and may glorify the Name.
Ignatius, Smyrnaeans 12 250 AD
I salute your godly bishop and your venerable presbytery and my fellow-servants the deacons, and all of you severally and in a body...
[source: articles "Deacon" and "Deaconess," both by Everett Ferguson, in Encyclopedia of Early Christianity, ed. E. Ferguson et al.]