Let God arise, let his enemies be scattered; let them also that hate him flee before him. Compare the chant with which the ark set forth in the wilderness, "Rise up, Lord, and let thine enemies be scattered; and let them that hate thee flee before thee" (Numbers 10:35).
Both utterances are expressions of confidence, that, whenever God arises, his enemies will be scattered and dispersed before him. Neither refers to any one special occasion.