Rashi on Deuteronomy 33:26/רש"י על דברים ל״ג:כ״ו

1אין כאל ישרון THERE IS NONE LIKE GOD, O JESHURUN — Know, O Israel, that there is none like God among all the gods of the peoples, and that their rock is not as your Rock.

2רכב שמים — The meaning is: A RIDER UPON THE HEAVEN is the God who is your help, ובגאותו שחקים AND IN HIS MAJESTY he rides UPON THE SKIES.