Exodus 17:8-16

Then Amalek came and fought with Israel¹ at Rephidim. Moses said to Joshua,² ‘Choose some men for us and go out; fight³ with Amalek. Tomorrow I will stand on the top of the hill with the staff of God⁴ 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;⁵ 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. 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 sun set.⁶ And Joshua defeated Amalek and his people with the sword.⁷
Then the Lord said to Moses, ‘Write this as a reminder in a book and recite it in the hearing of Joshua: I will utterly blot out the remembrance of Amalek from under heaven.’⁸
And Moses built an altar and called it, The Lord is my banner. He said, ‘A hand upon the banner of the Lord! The Lord will have war with Amalek⁹ from generation to generation.’

1 It is not specified why Amalek chose to fight Israel. Possibilities include that he feared them, that they were encroaching on his people's land, or that he desired to gain bounty from them.

2 Joshua is introduced as the one who leads the fighting for Israel.

3 The first time in the Exodus narrative that God's people choose the sword.

4 Moses implies that the fighting will be under God's control.

5 Israel's ability to prevail in the fight is clearly linked to God alone.

6 Extra narration is given to emphasize Moses's gesture to God far more than the actual events of the fighting.

7 The sword is given a positive tint.

8 God clearly has something against Amalek. And he makes it clear that he, not Israel, has defeated Amalek.

9 The Lord is the one who will continue fighting with Amalek.

Take-home: Like the stories of miraculous water, food, or defense from Egypt, God's provision is shown in yet another way. For the first time, the use of the sword by Israel is part of how God's miracle is worked out. However, the focus in the text is on God's work – he is the one who had something against Amalek and his people, he is the one who brought victory, and he is the one who will continue fighting against Amalek.