Exodus 15:27

21 And Miriam, answering, said, Make a song to the Lord, for he is lifted up in glory; the horse and the horseman he has sent into the sea.

22 Then Moses took Israel forward from the Red Sea, and they went out into the waste land of Shur; and for three days they were in the waste land where there was no water.

23 And when they came to Marah, the water was no good for drinking, for the waters of Marah were bitter, which is why it was named Marah.

24 And the people, crying out against Moses, said, What are we to have for drink?

25 And in answer to his prayer, the Lord made him see a tree, and when he put it into the water, the water was made sweet. There he gave them a law and an order, testing them;

26 And he said, If with all your heart you will give attention to the voice of the Lord your God, and do what is right in his eyes, giving ear to his orders and keeping his laws, I will not put on you any of the diseases which I put on the Egyptians: for I am the Lord your life-giver.

27 And they came to Elim where there were twelve water-springs and seventy palm-trees: and they put up their tents there by the waters.