Revelation 4:6-8

Also in front of the throne there was what looked like a sea of glass, clear as crystal. In the center, around the throne, were four living creatures, and they were covered with eyes, in front and in back. The first living creature was like a lion, the second was like an ox, the third had a face like a man, the fourth was like a flying eagle. Each of the four living creatures had six wings and was covered with eyes all around, even under its wings. Day and night they never stop saying