Revelation 1:10

Vision of the Son of Man, Revelation 1:10-20

10. I was in the spirit Was caught into a state of spiritual rapture. Song of Solomon 4:2 and (nearly) Revelation 17:3; Revelation 21:10; cf. 1 Kings 18:12; Ezekiel 3:12; Ezekiel 3:14; Ezekiel 37:1; also 2 Corinthians 12:2-3.

the Lord's day Undoubtedly here used (though for the first time) in the sense now traditional throughout Christendom. Many of the early Fathers, Ignatius, Justin Martyr, Clement of Alexandria, Tertullian, &c. use the word of the First Day of the week. A few commentators have proposed to translate, "I was, in spirit, on the day of the Lord," i.e. was carried away in spirit to the Great Day of the Lord's Coming; but the reference to Revelation 4:2 refutes this.

as of a trumpet As loud, and perhaps as clear.