The Hebrew children are going through God's boot camp. He's already shown them that He could provide water and food. He's given them a simple commandment to obey to see how well they could follow orders.
Exodus 17:1-3- And all the 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. Wherefore the people did chide with Moses, and said, Give us water that we may drink. And Moses said unto them, Why chide ye with me? wherefore do ye tempt the LORD? And the people thirsted there for water; and the people murmured against Moses, and said, Wherefore is this that thou hast brought us up out of Egypt, to kill us and our children and our cattle with thirst?
Why do they keep saying that Moses brought them out of Egypt to kill them? What would make them think that?
Exodus 17:4-7- And Moses cried unto the LORD, saying, What shall I do unto this people? they be almost ready to stone me. And the LORD said unto Moses, Go on before the people, and take with thee of the elders of Israel; and thy rod, wherewith thou smotest the river, take in thine hand, and go. 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. 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?
Moses obeyed God and took his rod and hit a rock in Horeb. The rock gushed out water and the people drank! God had proven once again that He could take care of their needs.
But, the people of the Lord are never without trouble for very long. The devil always seems to have someone who is ready to stop them from reaching the goal that God has set for them.
Exodus 17:8-9- Then came Amalek, and fought with Israel in Rephidim. 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.
Amalek wanted to fight with the Hebrew children. Moses told Joshua to take some men and go out to fight.
Who was Joshua? How were these slaves suppose to fight?
Exodus 24:13a- And Moses rose up, and his minister Joshua:
Joshua was the guy that made sure Moses had what he needed. And right now, Moses needed an army captain. So, guess who got the job?
Joshua went and chose out some strong men who looked like they could fight.
Exodus 17:10-11- 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. And it came to pass, when Moses held up his hand, that Israel prevailed: and when he let down his hand, Amalek prevailed.
Joshua was fighting his hardest. But the battle was long!
Exodus 17:12-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.
Some times, a man of God needs a little help or encouragement. Moses certainly did. Aaron and Hur stepped up to the task. They put a stone for Moses to sit on and they helped him hold his hands up so that Joshua could win the battle.
Exodus 17:13-16- And Joshua discomfited Amalek and his people with the edge of the sword. 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. And Moses built an altar, and called the name of it Jehovahnissi: For he said, Because the LORD hath sworn that the LORD will have war with Amalek from generation to generation.
Not since the flood had God sworn to destroy a people. But the Lord was going to annihilate the Amalekites. And he was going to prepare the children of Israel to be the army He needed to eventually do that.