Paul’s letter to the Ephesians before Ephesians (Ephesians 3:3 “As I wrote afore in few words...”)
An unknown messianic prophecy possibly from a non-canonical source, quoted in Matthew 2:23 that states "...he will be called a Nazorian." ("ὅτι Ναζωραῖος κληθήσεται"). "Nazorian" is typically rendered as "Nazarene" ("from Nazareth"), as in Acts 24:5, where Christians are referred to as "the sect of the Nazorians/Nazarenes" ("τῶν Ναζωραίων αἱρέσεως"). This is speculated to be a vague allusion to a quote about Samson in Judges 13:5 that uses a similar-sounding word: "the child shall be a Nazirite" (ναζιρ)
An unknown version of Genesis (possibly a targum, midrash or other commentary), quoted by Paul in 1 Corinthians 15:45, as a reference to Christ's being "the Last Adam who became a life-giving spirit" (οὕτως καὶ γέγραπται· Ἐγένετο ὁ πρῶτος ἄνθρωπος Ἀδὰμ εἰς ψυχὴν ζῶσαν· ὁ ἔσχατος Ἀδὰμ εἰς πνεῦμα ζῳοποιοῦν.). It has been speculated that Paul is simply paraphrasing Genesis 2:7, but there is no clear indication that this is not a complete quote.
An unknown text quoted by Paul in 1 Corinthians 2:9, suggested by Origen to be a lost apocryphal book: "But as it is written, 'No eye has seen, no ear has heard, and no mind has imagined the things that God has prepared for those who love him." This may also be an allusion to the similar Isaiah 64:4, "For from days of old they have not heard or perceived by ear, nor has the eye seen a God besides You, Who acts in behalf of the one who waits for Him.'".
An unknown messianic prophecy, possibly from a non-canonical source, quoted in Luke 24:46, speculated to be a vague allusion to Hosea 6:2: "Thus it is written, and thus it behoved Christ to suffer, and to rise from the dead the third day."
An unknown messianic prophecy, possibly from a non-canonical source, quoted in Mark 9:12, speculated to be a vague allusion to Isaiah 53: "and how it is written of the Son of man, that he must suffer many things, and be set at nought."