In Egypt the people had forgotten the Sabbath. Now the Lord would have them remember it. So on the seventh day no manna was given. But on the sixth day the people gathered enough for two days.
And the Lord kept it sweet for them over the Sabbath. This was a Sabbath lesson for them every week. The Sabbath was made for man, and given to him at creation as a memorial of God's great work of making the world in six days. But Israel had forgotten. God wants His Sabbath kept holy now as well as in the time of Israel in the wilderness.
Water from the Rock.
When they came to Rephidim there was no water, and the people complained again to Moses. And the Lord told Moses to go to Mount Horeb and smite the rock with his staff. When he did so, water burst from the rock, enough for the whole camp. It was Moses who smote the rock, but the Lord made the waters to flow.
Whenever the camp was pitched after this they found good water flowing from the rock for them. This rock was to make them and us think of Christ, and the water flowing from it represents the living water of the Word of God which He gives to all who want it.
Soon a new danger arose. The Amalekites came out to attack them. Joshua led the armies of Israel against them. While the battle was going on, Moses stood on a hill and raised his hands to God and prayed for the success of Israel. When he became weary and lowered his hands, the Amalekites were successful. Then Aaron and Hur held up the hands of Moses until the sun went down, and Israel gained the victory.
This was to teach Israel that the victory came from God, and that he would hear and answer prayer. It also taught them that they should help their leader, Moses, in the great work he had to do.