Exodus 17:8-13

8 Then came Amalek, and fought with Israel in Rephidim.
9 And Moses said unto Joshua,[a] Choose us out men, and go out, fight with Amalek: to morrow I will stand on the top of the hill with the rod of God in mine hand.
10 So Joshua did as Moses had said to him, and fought with Amalek: and Moses, Aaron, and Hur went up to the top of the hill.
11 And it came to pass, when Moses held up his hand, that Israel prevailed: and when he let down his hand, Amalek prevailed.
12 But Moses' hands were heavy; and they took a stone, and put it under him, and he sat thereon; and Aaron and Hur stayed up his hands, the one on the one side, and the other on the other side; and his hands were steady until the going down of the sun.
13 And Joshua discomfited Amalek and his people with the edge of the sword.

Exodus 17:8-13 Meaning and Commentary

INTRODUCTION TO EXODUS 17

The children of Israel coming to Rephidim, want water, and chide with Moses about it, who, crying to the Lord, is bid to smite the rock, from whence came water for them, and he named the place from their contention with him, Ex 17:1-7 at this place Amalek came and fought with Israel, who, through the prayer of Moses, signified by the holding up of his hands, and by the sword of Joshua, was vanquished, Ex 17:8-13, for the remembrance of which it was ordered to be recorded in a book, and an altar was built with this inscription on it, "Jehovahnissi": it being the will of God that Amalek should be fought with in every generation until utterly destroyed, Ex 17:14-16.

Exodus 17:8-13 In-Context

6 Behold, I will stand before thee there upon the rock in Horeb; and thou shalt smite the rock, and there shall come water out of it, that the people may drink. And Moses did so in the sight of the elders of Israel.
7 And he called the name of the place Massah, and Meribah, because of the chiding of the children of Israel, and because they tempted the LORD, saying, Is the LORD among us, or not?
8 Then came Amalek, and fought with Israel in Rephidim.
9 And Moses said unto Joshua, Choose us out men, and go out, fight with Amalek: to morrow I will stand on the top of the hill with the rod of God in mine hand.
10 So Joshua did as Moses had said to him, and fought with Amalek: and Moses, Aaron, and Hur went up to the top of the hill.
11 And it came to pass, when Moses held up his hand, that Israel prevailed: and when he let down his hand, Amalek prevailed.
12 But Moses' hands were heavy; and they took a stone, and put it under him, and he sat thereon; and Aaron and Hur stayed up his hands, the one on the one side, and the other on the other side; and his hands were steady until the going down of the sun.
13 And Joshua discomfited Amalek and his people with the edge of the sword.
14 And the LORD said unto Moses, Write this for a memorial in a book, and rehearse it in the ears of Joshua: for I will utterly put out the remembrance of Amalek from under heaven.
15 And Moses built an altar, and called the name of it Jehovahnissi:

Footnotes 1

The King James Version is in the public domain.