A.T. Robertson Commentary Revelation 10:8

"And the voice which I heard from heaven, [I heard it] again speaking with me, and saying, Go, take the book which is open in the hand of the angel that standeth upon the sea and upon the earth." — Revelation 10:8 (ASV)

Again speaking and saying (παλιν λαλουσαν κα λεγουσαν). Present active predicate participles feminine accusative singular agreeing with ην (object of ηκουσα), not with φωνη (nominative) as most of the cursives have it (λαλουσα κα λεγουσα). Ordinarily it would be ελαλε κα ελεγεν. See 4:1 for like idiom. This is the voice mentioned in verse 4. No great distinction is to be made here between λαλεω and λεγω.

Go, take (Hυπαγε λαβε). Present active imperative of υπαγω and second aorist active imperative of λαμβανω. The use of υπαγε (exclamation like ιδε) is common in N.T. (Matthew 5:24; Matthew 8:4; Matthew 19:21; John 4:16; John 9:7). Charles calls it a Hebraism (16:1). Note the repeated article here (το) referring to the open book in the hand of the angel (verse 2), only here βιβλιον is used, not the diminutive of βιβλαριδιον of verses 2,9,10.