And one of the elders saith unto me, Weep not: behold, the Lion of the tribe of Juda, the Root of David, hath prevailed to open the book, and to loose the seven seals thereof. One of - `one from among.' The 'elder' is, according to some (in Lyra), Matthew. With this accords the description, "the Lion, which is of the tribe of Juda, the Root of David:" the royal, David-descended, lion-aspect of Christ being prominent in Matthew, whence the lion among the fourfold cherubim is assigned to him. Gerhard thought Jacob meant, and that he was one of those who rose with Christ and ascended to heaven (Matthew 27:52-53): cf. his words, "Judah is a LION'S whelp," etc. The elders round God's throne know better than John, still in the flesh, Christ's far-reaching power.
Root of David - (Isaiah 11:1; Isaiah 11:10.) Not mealy 'a sucker from David's ancient root' (as Alford), but also Himself the root and origin of David. Compare these two brought together, Matthew 22:42-45. Hence, He is not merely Son of David, but also David (Ezekiel 34:23-24; Ezekiel 37:24-25). He is at once "the branch" and "the root" of David, David's Son and David's Lord, the Lamb slain, therefore the Lion of Juda: about to reign over Israel, and thence over the whole earth.
Prevailed - `conquered' absolutely, as Revelation 3:21: His past victory over all the powers of darkness entitles Him to open the book.
To open. So A, Vulgate, Coptic, Origen; but B, 'he that openeth' - i:e., whose office is to open.