Water from the rock. Joshua leads Israel to defeat Amalek.

Exodus 17

The whole congregation of the children of Israel journeyed from the wilderness of Sin, after their journeys, according to the commandment of the LORD, and pitched in Rephidim: and there was no water for the people to drink.

2 So the people quarreled with Moses, and said “Give us water that we may drink.” And Moses said to them “Why do you quarrel with me? Why do you tempt the LORD?”

3 The people were thirsty for water and grumbled against Moses, and said “Why is it that you have brought us up out of Egypt, to kill us and our children and our livestock with thirst?” 

4 And Moses cried out to the LORD “What will I do with these people? They are almost ready to stone me.”

5 The LORD said to Moses “Go on ahead of the people, and take some of the elders of Israel with you, and take your staff that you struck the river with in your hand, and go.

6 Behold, I will stand before you there on the rock in Horeb; and you shall strike the rock, and water will come out of it, that the people may drink.” And Moses did so in the sight of the elders of Israel.

7 He called the name of the place Massah, and Meribah, because of the quarreling of the children of Israel, and because they tempted the LORD, saying “Is the Lord among us, or not?”

8 Then Amalek came and fought with Israel in Rephidim.

9 Moses said to Joshua “Choose men for us and go out, fight with Amalek: tomorrow I will stand on the top of the hill with the staff of God in my hand.”

10 So Joshua did as Moses said to him, and fought with Amalek: and Moses, Aaron, and Hur went up to the top of the hill.

11 When Moses held up his hand, 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 on it; and Aaron and Hur held up his hands, the one on the one side, and the other on the other side; and his hands were steady until the sun went down.

13 Joshua defeated Amalek and his army with the sword.

14 The LORD said to Moses “Write this for a memorial in a book, and rehearse it in the ears of Joshua: for I will utterly put Amalek out of remembrance from under heaven.”

15 And Moses built an altar, and called the name of it The LORD is my banner. 

16 For he said “Because the Lord has sworn that the LORD will have war with Amalek from generation to generation.”

See also: Exodus 17 in ESV, HCSB, NASB and NIV at Bible Gateway.