In Exodus 17:8-16 we read of Amalek fighting with the children of Israel at Rephidim. To the top of the hill ascended Moses with the rod of God in his hand, accompanied by Aaron and Hur. When Moses held up his hand, Israel prevailed; when he let down his hand, Amalek prevailed. Moses' hands, however, growing heavy, Aaron and Hur placed him sitting on a stone, while they propped up his hands till the setting of the sun. So Joshua discomfited Amalek and his people with the edge of the sword.
In this we have a beautiful type of our Lord's intercession on high for His people, fighting as they are with the enemy—the world, the flesh, the Devil. Yet how vivid is the contrast. Moses' hands, being heavy with age, needing to be propped up; our High Priest, the Lord Jesus Christ, living after the power of an endless life (Heb. 7:16). No hanging down of His blessed hands. No failure with Him. What brings failure and humiliation to us is our failure to avail ourselves of the wonderful resources we have in our Lord for our support in the fight. There is nothing but victory with Him.
We read that in consequence of this victory over Amalek, "Moses built an altar, and called the name of it JEHOVAH-NISSI [The LORD my banner]." (Ex. 17:15).
Under such a banner only victory is possible.