Revelation 1:10 - Matthew Poole's English Annotations on the Holy Bible

I was in the Spirit; not only in spiritual employment, suppose meditation and prayer, but in an ecstasy; my soul was (as it were) separated from my body, and under the more than ordinary influence and communications of the Spirit, as Acts 10:10, Acts 11:5 16:9 18:9. On the Lord's day; upon the Christian sabbath, called the Lord's day, (as the eucharist, or breaking of bread, is called the Lord's supper, 1 Corinthians 11:20), because Christ instituted it; or, because the end of its institution was the remembrance of Christ's resurrection, (as the end of the Lord's supper was the commemoration of Christ's death), or because it was instituted for the honour of Christ. And heard behind me a great voice, as of a trumpet: John in the isle of Patmos was keeping the Christian sabbath in spiritual services, meditation and prayer, and fell into a trance, wherein he had a more immediate communion with the Holy Spirit, which begun with his hearing a loud voice, as it were, behind him, as loud as the sound of a trumpet.