My reading project on the concept of tradition commences in earnest with Origen’s De Principiis (I use John Behr’s translation, with minor punctuation and formatting alterations):

All who believe and are assured that “Grace and truth came through Jesus Christ,” and who know Christ to be the truth, according to his saying, “I am the truth,” derive the knowledge which leads human beings to live a good and blessed life from no other source than from the very words and teaching of Christ. And by “the words of Christ” we mean not only those which he spoke when he became human and dwelt in the flesh; for even before this, Christ, the Word of God, was in Moses and the prophets… And that he also spoke, after his ascension into heaven, in his apostles, is shown by Paul in this way, “Or do you seek a proof of Christ who speaks in me?” [Pr.1.]

Since, however, many of those who profess to believe in Christ differ not only in small and trivial matters, but even on great and important matters — such as concerning God or the Lord Jesus Christ or the Holy Spirit, and not only regarding these but also regarding matters concerning created beings, that is, the dominions and the holy powers — it seems necessary first of all to lay down a definite line and clear rule [Gk Vorlage: kanon?] regarding each one of these matters, and then thereafter to investigate other matters. … [Although] there are many who think that they know what are the teachings of Christ, and not a few of them think differently from those before them, one must guard the ecclesiastical preaching, handed down from the apostles through the order of succession and remaining in the churches to the present: that alone is to be believed to be the truth which differs in no way from the ecclesiastical and apostolic tradition. [Pr.2.]

[The] holy apostles, in preaching the faith of Christ, delivered with utmost clarity to all believers, even to those who seemed somewhat dull in the investigation of divine knowledge, certain points that they believed to be necessary, leaving, however, the grounds of their statements to be inquired into by those who should merit the excellent gifts of the Spirit and especially by those who should receive from the Holy Spirit himself the grace of language, wisdom, and knowledge; while on other points they stated that things were so, keeping silence about how or whence they are, certainly so that the more diligent of their successors, being lovers of wisdom… might have an exercise on which they might display the fruit of their ability. [Pr.3.]