Although most discussions about the development of the canon focus on the patristic period (second century and later), there is much canonical gold yet to mine from the pages of the New Testament itself. One passage that I think contains a number of intriguing clues is 2 Cor 3:14 when Paul says, “When they read the Old Covenant, that same veil remains unlifted.”
Often overlooked in this passage is that Paul understands a covenant to be something that you read; i.e., covenants are written documents. When we look at Paul’s Jewish context this should come as no surprise. So close is the relationship between the covenant, and the written documentation of the covenant, that Old Testament authors would frequently equate the two—the covenant, in one sense, is a written text.
For instance: “Then he took the book of the covenant and read it” (Ex 24:7; cf. 1 Macc 1:57); “And he read in their hearing all the words of the book of the covenant” (2 Kings 23:2; cf. 2 Chron 34:30); “He declared to you his covenant…that is, the Ten Commandments, and he wrote them on two tablets (Deut 4:13); “He wrote on the tablets the words of the covenant” (Ex 34:28); and “The covenant written in this book” (Deut 29:21). These passages indicate that covenants were largely conceived as something written or read; i.e., something in a book. It is precisely for this reason that warning were given not to change the text of the covenant (Deut 4:2), and there were concerns about it being in the proper physical location (Ex 25:16).
If so, then what shall we make of Paul’s statement in 2 Cor 3:6 that he and the other apostles are “ministers of a new covenant”? Given Paul’s statement in 2 Cor 3:14 that we just noted, it would be natural to think that Paul has in mind a new set of written documents that testify to the terms of the new covenantal arrangement in Christ. As Carmignac argues, “In order to use the expression ‘Old Testament’ he [Paul] must also be aware of the existence of a ‘New Testament.’” Carmignac even goes further and suggests that this ‘New Testament’ may have had contained a number of books in order for it to be parallel with the Old.
The likelihood that Paul views the new covenant as having written documents increases when we make the simple observation that Paul is claiming for himself this distinctive covenantal authority within a written letter to the Corinthians. And scholars have observed how this very letter functions as a “covenant lawsuit”against the Corinthians. Thus, one could hardly fault the Corinthians if they regarded the letter itself as bearing some sort of covenantal authority.
All in all, 2 Cor 3:14 provides a number of curious clues about the origins of a new canon of Scripture.
 Jean Carmignac, “II Corinthiens III. 6, 14 et le Début de la Formation du Noveau Testament,” NTS 24 (1977): 384-386, at 385 (translation mine). (386).
 Lane, “Covenant: The Key to Paul’s Conflict with Corinth,” 3-29.