Irenaeus of Lyons, Against Heresies 3.1
We have come to know the plan of our salvation through others — through those, that is, by whom the Gospel first reached us. They proclaimed it beforehand; then, by God's will, they committed it to Scripture so that it would become the foundation and pillar of our faith. It is not permissible to claim that they preached before they possessed perfect knowledge, yet some have the audacity to say exactly that, boasting that they are the correctors of the Apostles.
For after our Lord rose from the dead, and they were clothed with the power of the Holy Spirit descending from on high, they were filled with all things and attained perfect knowledge. They went out to the ends of the earth, preaching the good things God has prepared for us and announcing heavenly peace to humanity — each and all of them bearing the Gospel of God.
Thus Matthew, writing in the Hebrews' own tongue, published his Gospel while Peter and Paul were evangelizing in Rome and founding the Church. After their departure, Mark, disciple and interpreter of Peter, handed down to us in writing what Peter had proclaimed. Luke, a follower of Paul, set down in a book the Gospel that Paul preached. Later, John, the Lord's disciple who had reclined on His breast, published his Gospel while living in Ephesus of Asia.
All these men delivered to us one God, the Maker of heaven and earth, announced by the Law and the Prophets, and one Christ, the Son of God. If anyone refuses to assent to this testimony, he despises the companions of the Lord; he despises Christ the Lord Himself; he despises the Father; and he stands self-condemned, resisting and opposing his own salvation — which is precisely what all heretics do.
Latin
1. Now enim per alios dispositionem salutis nostree cognovimus, quam per eos per quos Evangelium pervenit ad nos: quod quidem tune preeconayerunt, postea vero per Dei voluntatem in Seripturis nobis tradiderunt, fundamentum et columnam fidei nostree futurum. Nec enim fas est dicere, quoniam ante preedicaverunt quam perfectam haberent agnitionem; sicut quidam audent dicere, gloriantes emendatores se esse Apostolorum. Postea enim quam surrexit Dominus noster a mortuis, et induti sunt supervenientis Spiritus sancti virtutem ex alto, de omnibus adimpleti sunt, et habuerunt perfectam agnitionem; exierunt in fines terree, ea quee a Deo nobis bona sunt evangelizantes, et ccelestem pacem hominibus annuntiantes, qui quidem et omnes pariter et singuli eorum habentes Evangelium Dei*. Ita Mattheus in Hebreis ipsorum lingua scripturam y. edidit Evangelii, cum Petrus et Paulus Rome evangelizarent, et ecxdyoiav. Mera de trav fundarent Ecclesiam. Post vero horum excessum, Marcus discipulus et interpres Petri, et ipse quee a Petro annuntiata erant, per ———— seripta nobis tradidit. Et Lucas autem sectator Pauli, quod ab illo preedicabatur Evangelium, in libro condidit. Postea et Johannes discipulus Domini, qui et supra pectus ejus recumbebat, et ipse edidit Evangelium, Ephesi Asie commorans. Et omnes isti unum Deum factorem cceli et terre a lege et prophetis annuntiatum, et unum Christum filium Dei tradiderunt nobis: quibus si quis non assentit, spernit quidem participes Domini, spernit autem et ipsum Christum Dominum, spernit vero et Patrem, et est a semetipso damnatus, resistens et repugnans saluti suze: quod faciunt omnes heeretici.