In spite of a batcrap crazy thesis (Paul did not write any of the letters attributed to them, and they were all composed after the Bar-Kochba revolt; ergo, 1 Clement and other works are much later than traditionally dated, etc), Nina E. Livesey is forced to concede that 1 Clement does indeed quote the Pauline epistles (showing Paul’s epistles predates 1 Clement [traditionally mid-90s, though I hold to the theory it was written in the year 69, just before the destruction of the Second Temple]):
First Clement, however, is
aware of Pauline letters. It certainly knows I Corinthians. In an often-cited
passage, the leaders in Rome (the purported letter senders) urge the Corinthian
addressees to "take up the epistle of the blessed Paul the apostle" (I
Clem. 47.1). Yet it is likely that I Clement is also aware of other
Pauline letters, including especially Romans. The vice list (I Clem.
35.5-6) is the best evidence that I Clement knew Romans (1:29-32). While I
Clement lists fewer vices than Romans, the two inventories begin and end
with formulae that harmonize in content and language. Barnett finds verbal
agreement between Rom 9:4 and I Clem. 32.2 and stylistic agreement
between Rom 6:1 and I Clem. 33.1. Moreover, the narrative setting as
envisioned in I Clement - a letter that claims to be from a community in Rome -
is itself suggestive that the author knew of the Pauline letter to the Romans.
Using a similar methodology as
the one used to indicate literary dependency on I Corinthians and Romans,
Barnett also finds it probable that I Clement made use of 2 Corinthians,
Galatians, Ephesians, and Philippians. In addition, it seems clear that I
Clement knew Hebrews (I Clem. 36.2 [Heb I:3-4]; I Clem. 36.3 [Heb
1:7]; I Clem. 36.4 [Heb I:5]; I Clem. 36.5 [Heb I:13]). (Nina E.
Livesey, The Letters of Paul in their Roman Literary Context: Reassessing
Apostolic Authorship [Cambridge: Cambridge University Press, 2024], 117-18)