Revelation 4:6, 8

Also before the throne there was something that looked like a sea of glass, clear like crystal. In the center and around the throne were four living creatures with eyes all over them, in front and in back.

Each of these four living creatures had six wings and was covered all over with eyes, inside and out. Day and night they never stop saying: “Holy, holy, holy is the Lord God Almighty. He was, he is, and he is coming.”