Early Second Century Literature: Epistle of Clement

First Epistle of Clement 42:

The Apostles received the gospel for us from the Lord Jesus Christ, Jesus the Christ was sent from God. The Christ therefore is from God and the apostles  from the Christ. In both ways, then, there were in accordance with the appointed order of God's will. Having therefore received their commands, and being fully assured by the resurrection of our Lord Jesus Christ, and with faith confirmed by the word of God, they went forth in the assurance of the Holy spirit preaching the good news that the kingdom of God is coming. They preached from district to district, and from city to city, and they appointed their first converts, testing them by the Spirit, to be bishops and deacons of the future believers. And this was no new method, for many years before had bishops and deacons been written of: for the scripture says thus in one place: 'I will establish their bishops in righteousness and their deacons in faith'. (Taking from Isaiah 60.27).

First Epistle of Clement 44: 

Our Apostles also knew through our Lord Jesus Christ, that there would be strife for the title of bishop. For this cause, therefore, since they had received perfect knowledge, they appointed those who had already been mentioned, and afterwards gave them the direction that if they should fall asleep, other well-tried men should succeed to their ministry (εαν κοιμηθωσιν, διαδεξωνται ετεροι δεδοκιμασμενοι ανδρες την λειτουργιαν αυτων). We consider therefore that it is not just to remove from their ministry those who were appointed by them, or later on by other eminent men with the consent of the whole Church. 

First Epistle of Clement 7.2-5:

Let us put aside empty and vain cares, and let us come to the glorious and venerable rule of our tradition (τον της παραδοσεως κανονα), and let us see what is good and pleasing and acceptable in the sight of our Maker. Let us fix our gaze on the Blood of Christ, and let us know what it is precious to his Father, because it was poured out for the salvation, and brought the grace of repentance to all the world. Let us review all the generations, and let us learn in generation after generation the Master has given him a place of repentance to those who will turn to him.