Gregory probably has 2 Cor 3:3 in mind, where Paul writes that the Corinthians are “a letter of Christ… written not with ink (μέλανι) but by the Spirit of the Living God, not in tablets (ἐν πλαξί) of stone, but in tablets that are hearts of flesh.”

Note the juxtaposed prosodic variants:

• Πατρός (2: trochee –  ⏑; 4: pyrrhus ⏑ ⏑; 7: spondee – –)
• λόγον (1: pyrrhus ⏑ ⏑, 3: iamb ⏑ –, lengthened by position)
• τόσον, ὅσσον, τόσσον (9, 11)

cf. Callimachus, Aetia, fr. 1.4–5: εἵνεκεν οὐχ ἓν ἄεισμα διηνεκὲς ἢ βασιλ[η ....]ας ἐν πολλαὶς ἤνυσα χιλιάσιν

"[They criticize me] Because I haven't completed one continuous song in many thousands of lines."

Or, "with pen that has no ink." Gregory puns on the meaning of μέλαν, which could mean either "ink" or "stain."

Note the repetition of both first half lines 1–2 in lines 3–4.

Cf. Callimachus Aetia, fr. 1.9: ὀλιγόστιχος, ἀλλὰ καθλέλκει.