Ephesians 1:13

In whom ye also--Ye Gentiles. Supply as English Version, "trusted," from Eph 1:12; or "are." The priority of us Jews does not exclude you Gentiles from sharing in Christ (compare Act 13:46). the word of truth--the instrument of sanctification, and of the new birth (Joh 17:17; Ti2 2:15; Jam 1:18). Compare Col 1:5, where also, as here, it is connected with "hope." Also Eph 4:21. sealed--as God's confirmed children, by the Holy Spirit as the seal (Act 19:1-6; Rom 8:16, Rom 8:23; Jo1 3:24; see on Co2 1:22). A seal impressed on a document gives undoubted validity to the contract in it (Joh 3:33; Joh 6:27; compare Co2 3:3). So the sense of "the love of God shed abroad in the heart by the Holy Ghost" (Rom 5:5), and the sense of adoption given through the Spirit at regeneration (Rom 8:15-16), assure believers of God's good will to them. The Spirit, like a seal, impresses on the soul at regeneration the image of our Father. The "sealing" by the Holy Spirit is spoken of as past once for all. The witnessing to our hearts that we are the children of God, and heirs (Eph 1:11), is the Spirit's present testimony, the "earnest of the (coming) inheritance" (Rom 8:16-18). that Holy Spirit of promise--rather, as the Greek, "The Spirit of promise, even the Holy Spirit": The Spirit promised both in the Old and New Testaments (Joe 2:28; Zac 12:10; Joh 7:38-39). "The word" promised the Holy Spirit.

— Jamieson-Fausset-Brown Commentary (public domain)