Apocalipse 4

Apocalipse 4:8

For what is nearer [God] than the cherubim or the seraphim? And yet they, not even seeing him or standing on their feet, or even with bare, but as it were with veiled faces, offer their praises, with untiring lips doing nothing else but glorifying the divine and ineffable nature with the Trisagion.… For the Triad, praised, reverenced and adored, is one and indivisible and without degrees. It is united without confusion, just as the Monad also is distinguished without separation. For the fact of those venerable living creatures offering their praises three times, saying "Holy, holy, holy," proves that the three Subsistences are perfect, just as in saying "Lord," they declare the one Essence. — ON LUKE 10:22