A.T. Robertson Commentary Revelation 5:8

"And when he had taken the book, the four living creatures and the four and twenty elders fell down before the Lamb, having each one a harp, and golden bowls full of incense, which are the prayers of the saints." — Revelation 5:8 (ASV)

He had taken (ελαβεν). Here John drops back to the narrative tense (the second aorist active indicative of λαμβανω), not the past perfect as the English rendering might indicate, merely "when he took." For like vivid variation (not confusion) of tenses with ειληφεν see 3:3; 8:5; 11:17 and with ειρηκα in 7:13f.; 19:3.

Fell down (επεσαν). Second aorist active indicative of πιπτω with first aorist (-αν) ending, just "fell."

Having (εχοντες). "Holding."

A harp (κιθαραν). Old word, the traditional instrument (lyre or zithern) for psalmody (Psalms 33:2; 98:5, etc.).

Golden bowls (φιαλας χρυσας). Broad shallow saucers, old word, in N.T. only in Re 5:8; 15:7; 16:1-4,8,10,12,17; 17:1; 21:9.

Of incense (θυμιαματων). Old word from θυμιαω, to burn incense (Luke 1:9), as in Lu 1:10.

Which are (α εισιν). "Which (these bowls of incense) symbolize the prayers of the saints as in Ps 140:2; Luke 1:10.