Revelation 4:6

Revelation 15:2 NIV
And I saw what looked like a sea of glass glowing with fire and, standing beside the sea, those who had been victorious over the beast and its image and over the number of its name. They held harps given them by God

Revelation 5:6 NIV
Then I saw a Lamb, looking as if it had been slain, standing at the center of the throne, encircled by the four living creatures and the elders. The Lamb had seven horns and seven eyes, which are the seven spirits of God sent out into all the earth.