Apocalypse Explained #284
284. And they were full of eyes within. That this signifies the Divine providence and guardianship, is evident from the signification of eyes, when said of the Lord, as being His Divine providence (concerning which see above, n. 68 152). The reason why guardianship is also signified is that cherubim have also that signification (n. 277).
Revelation 9:9
9
They had breastplates, like breastplates of iron. The sound of their wings was like the sound of chariots, or of many horses rushing to war.