Targum zu Bamidbar 10:35

And it was when the ark should go forward, the Cloud gathered itself together and stood still, not going on, until Mosheh, standing in prayer, prayed and supplicated mercy from before the Lord, and thus spake: Let the Word of the Lord be now revealed in the power of Thy anger, that the adversaries of Thy people may be scattered; and let not the banner of those who hate them be uplifted before Thee.

It was when the ark went forward. Mosheh stood, with hands (outstretched) in prayer, and said, Arise now, O Word of the Lord, in the power of Thy might, and let the adversaries of Thy people be scattered, and make Thine enemies flee before Thee.