That future theophany occurs not at Mount Sinai but at Mount Zion (i.e., Jerusalem). At Mount Sinai, the LORD appeared in the midst of the cloud of glory that covered the mountain. At Mount Zion, “they will see the Son of Man coming in clouds with great power and glory”. From Sinai, the nation heard the sound of the trumpet; from Zion, the whole world will hear the sound of the trumpet. At Mount Sinai, God’s feet stood on the mountain and “under His feet there appeared to be a pavement of sapphire, as clear as the sky itself”, but “in that day His feet will stand on the Mount of Olives, which is in front of Jerusalem on the east”. - D. Thomas Lancaster, Two Trumpets