Ezekiel 1:18

As for their rings, they were so high that they were dreadful; and their rings were full of eyes round about them four.

Cross-reference

Ezekiel 10:12 explicitly repeats that the wheels and creatures were full of eyes all around, directly continuing the same visionary description.

Revelation 4:8 echoes this vision: the four living creatures are also full of eyes, depicting God's omniscience in heavenly worship.