I can’t believe that I bought two different commentaries, but the content is very similar. Please see the examples from Isaiah 6:4 from the different commentaries. 6:4 Finally, the prophet observed that the seraphs’ thunderous words of praise were causing the foundations of the doorway (either the threshold or the door pivots) to shake and the room “was being filled” with smoke. The smoke or cloud (Exod 19:16–18; 1 Kgs 8:10–11) is traditionally associated with God’s appearance and serves the function of concealing the awesome majesty of God from human eyes. Each of these experiences stresses the infinite distance between the world of man and the realm of God. Even reading about Isaiah’s experience strikes wonder and awe into a person’s heart; Isaiah is actually standing in the very presence of God Almighty. Smith, G. V. (2007). Isaiah 1–39 (E. R. Clendenen, Ed.; p. 191). B & H Publishing Group. 6:4 Finally, the prophet observed that the seraphs’ thunderous words of praise were causing the foundations of the doorway (either the threshold or the door pivots) to shake and the room to be filling with smoke. The smoke or cloud (Exod 19:16–18; 1 Kgs 8:10–11) is traditionally associated with God’s appearance and serves the function of concealing the awesome majesty of God from human eyes. Each of these experiences stresses the infinite distance between the world of man and the realm of God. Even reading about Isaiah’s experience strikes wonder and awe into a person’s heart; Isaiah is actually standing in the presence of God Almighty. Smith, G. V. (2021). Isaiah 1–39 (E. R. Clendenen & B. D. Smith, Eds.; pp. 208–209). Holman Reference.