Revelation 6:5
And when the Lamb broke open the third seal, I heard the third living being saying [to the one on the black horse ?], "Come [out]." So, I looked and before me [stood] a black horse, and the man riding on it had a pair of scales in his hand.
Revelation 4:6-7
And there was an ocean, as crystal-clear as glass, in front of the throne. And at the center, surrounding the throne were four living beings, covered with eyes in the front and back of them. [Note: In view of Isa. 6:1-3 and especially Eze. 10:20ff, these "living beings" appear to be some special order of heavenly beings who inhabit the presence of God].
Revelation 5:5
Then one of the [twenty-four] elders said to me, "Do not cry; look, the Lion from the tribe of Judah, the Root of King David, has gained the victory, so He can break the seven seals on the book and open it."
Revelation 5:9
And they sang a new song [which went like this]: "You deserve to take the book and break the seals on it, for you were killed and, with your blood, you purchased people for God from every tribe and language and race and nation,
Revelation 6:1
And I watched while the Lamb broke open one of the seven seals. Then I heard one of the four living beings saying in a thunderous voice [to the one on the white horse ?], "Come [out]."