2 Peter 3:18

αὐξάνετε ἐν χάριτι, cf. 2 Peter 1:8 πλεονάζοντα. αὐξάνω is oftener than not intransitive in N.T. but in classical Greek transitive, and so in 1 Corinthians 3:6 (ὁ θεὸς ηὔξανεν).

εἰς ἡμέραν αἰῶνος. An uncommon phrase: Sir 18:10 is quoted: as a drop of water out of the sea, or a grain of sand, οὕτως ὀλίγα ἔτη ἐν ἡμέρᾳ αἰῶνος. It is strange to find this expression in a doxology, where εἰς τοὺς αἰῶνας (τῶν αἰώνων) is almost invariable.