It seems clear from Psalm 68 that the display of external glory of fire on Mount Sinai was by the ministration of angels. This was the solemn sanction given to the law and its promulgation (Ex. 19:16-18). This is fully confirmed by Deuteronomy 33:2. Psalm 104:4 and 2 Kings 1:10; 6:17 afford analogous examples of Jehovah’s making His ministers a flame of fire. So even in the bush, when there was, as to its form, an angelic manifestation of God, the bush burned with fire. Moses spoke with the angel in the bush. What is particularly referred to in the passages we are considering is that the angels were the immediate instruments through which they received the law, the manifest glory which gave it its sanction — not that they spoke or personally addressed the people. That is, the functions of ambassadors are treated as akin to those of the angels, or divine legates. The character of authority attached to the law was angelic, not the incarnation of God Himself whether speaking on earth or from heaven. The whole of the first two chapters of Hebrews is to show the superiority of the Christian revelation to Judaism by that of Christ to angels, first as a divine person and second in the counsels of God as to the exaltation of man.
J. N. Darby