Then Amalek came and fought with Israel at Rephidim. So Moses said to Joshua, "Choose for us men, and go out and fight with Amalek. Tomorrow I will stand on the top of the hill with the staff of God in my hand." So Joshua did as Moses told him, and fought with Amalek, while Moses, Aaron, and Hur went up to the top of the hill. Whenever Moses held up his hand, Israel prevailed, and whenever he lowered his hand, Amalek prevailed. But Moses' hands grew weary, so they took a stone and put it under him, and he sat on it, while Aaron and Hur held up his hands, one on one side, and the other on the other side. So his hands were steady until the going down of the sun. And Joshua overwhelmed Amalek and his people with the sword. Then the LORD said to Moses, "Write this as a memorial in a book and recite it in the ears of Joshua, that I will utterly blot out the memory of Amalek from under heaven." And Moses built an altar and called the name of it, The LORD Is My Banner, saying, "A hand upon the throne of the LORD! The LORD will have war with Amalek from generation to generation."
Exodus 17:8-16
On the other hand, however, it is just as true that the blessing of God upon a people draws the attention of the enemy. After Sunday comes Monday morning. After the exalted experience at Jordan, Christ was led out into the wilderness to be tempted of the devil. After the glory of Pentecost came the fires of persecution. After the amazing outpouring of the Spirit that attended Paul’s missionary endeavours came the enemies of the Cross seeking to undo his work. In face of such satanic counter-attacks on the work of the Lord there can be only one expedient - prayer. It is this that the latter part of the passage stresses in its account of the intercession of Moses. This is the weapon which is mighty through God to the pulling down of strongholds and the spreading of confusion in the ranks of Amalek. The battle with Amalek is rich in spiritual lessons for us. In the first place there were two levels on which it was, and had to be, fought. There was the visible, material level, on which the hosts of Amalek had to be met, sword with sword, and vanquished on the field of battle; but there was also another level, on which Moses recognised that he had to do battle in the unseen, and lay hold on God for victory. Moses went up into the mount with the rod of God in his hand. It is difficult, in view of the obvious spiritual application of these verses, not to think of Moses in prayer on the mount, although it does not say that this is what he was doing. As a matter of fact, he held up the rod of God, as a standard-bearer holds up a standard in the midst of battle, as if to rally the unseen hosts of the Lord to the help of the Israelites, and to claim the mighty advocacy of the angel of the covenant.