296–373 AD: Athanasius quotes 1 John 5:7 twice in his Quaestiones Aliae
👉Greek: Ὥσπερ ἡ ψυχή µου µία ἐστὶν, ἀλλὰ καὶ τρισυπόστατος, ψυχὴ, λόγος, καὶ πνοή· οὕτω καὶ ὁ Θεὸς εἷς ἐστιν, ἀλλ' ἔστι καὶ τρισ υπόστατος, 'Πατὴρ, Λόγος, καὶ Πνεῦµα ἅγιον... Ὡς γὰρ ψυχὴ, λόγος καὶ πνοὴ τρία πρόσωπα, καὶ μία φύσις ψυχῆς, καὶ οὐ τρεῖς ψυχαί· οὕτω 'Πατὴρ, Λόγος καὶ Πνεῦμα ἅγιον, τρία πρόσωπα, καὶ εἷς τῇ φύσει Θεὸς, καὶ οὐ τρεῖς θεοί." (Page 3, Quaestiones Aliae-LINK)
English Translation:"Even as my soul is one, but a triune soul, reason, and breath; so also God is one, but is also triune, 'Father, Word, and Holy Ghost...For as soul, reason and breath are three features, and in substance one soul, and not three souls; so 'Father, Word and Holy Ghost, [are] three persons, and one God in substance, and not three gods." (Translation by KJV Today LINK)
Athanasius had Greek manuscripts of 1 John 5:7, mentioning direct words "'Πατὴρ, Λόγος καὶ Πνεῦμα ἅγιον" ('"Father, Word, and Holy Ghost") which together are from & in 1 John 5:7