Matthew Poole and continuators on Exodus 17:11

11 And it came to pass when Moses held up his hand , that Israel prevailed: and when he let down his hand Amalek prevailed .

With the rod of God in it. This gesture, though fervent prayer was doubtless joyned with it, seems not to have been the gesture of one praying, which is the lifting up of both hands, but of an Ensign-bearer, or of one ready to smite his enemies. Howsoever this was onely a sign whereby Moses strengthned his faith and quickned his prayers and heightned the courage of the Souldiers below, and protested that he expected victory not from the skill and prowess of his Army, but from the assistance of God.

God so dispensing his favour, that the honour of the day and victory might be wholly ascribed to the rod and power of God, not to Israel.