rideth. Figure of speech Anthropopatheia.
of old. Compare 2 Peter 3:5 and 2 Peter 3:6: referring to "the world that then was".
His voice. Omit the italics, and then we have the Figure of speech Epizeuxis, "His voice. voice of strength".
Related Commentaries of Psalms 68:33
Psalms 68:33
33 To him that rideth upon the heavens of heavens, which were of old; lo, he doth send out his voice, and that a mighty voice.