Verse 9:[1] I John, who also am your brother, and (Phil. 1:7; 4:14; 2 Tim. 1:8) companion in tribulation, and (Rom. 8:17; 2 Tim. 2:12) in the kingdom and patience of Jesus Christ, was in the isle that is called Patmos, (Rev. 6:9; 1:2) for the word of God, and for the testimony of Jesus Christ.
[I, John] Namely, that one already designated (Grotius). He expresses his name, for prophecy requires the authority of the writer (Pareus).
[Your brother] That is, of the same faith (Grotius, similarly Ribera, Menochius, Tirinus).
John, who also am your brother; the same mentioned Revelation 1:4, the apostle of Jesus Christ, yet he disdaineth not to call those his brethren whom his Lord so called.
[1] Greek: Ἐγὼ Ἰωάννης, ὁ καὶ ἀδελφὸς ὑμῶν καὶ συγκοινωνὸς ἐν τῇ θλίψει καὶ ἐν τῇ βασιλείᾳ καὶ ὑπομονῇ Ἰησοῦ Χριστοῦ, ἐγενόμην ἐν τῇ νήσῳ τῇ καλουμένῃ Πάτμῳ, διὰ τὸν λόγον τοῦ Θεοῦ καὶ διὰ τὴν μαρτυρίαν Ἰησοῦ Χριστοῦ.