Marah

Exodus 15:22-25a
 And Moses led Israel onward from the Red Sea, and they went out into the wilderness of Shur; and they went three days in the wilderness, and found no water. 23 And when they came to Marah, they could not drink of the waters of Marah, for they were bitter: therefore the name of it was called Marah. 24 And the people murmured against Moses, saying, What shall we drink? 25 And he cried unto Jehovah; and Jehovah showed him a tree, and he cast it into the waters, and the waters were made sweet . . . [ASV]
These verses describe the scene early after the Israelites departed Egypt.  The exhilaration of their escape had faded.  They were far from Egypt and found themselves in a wilderness.  Their water supplies were spent, they were tired, and needed refreshing.
They found water after arriving at Marah, but it couldn’t be consumed because it was too bitter.  They started a complaint campaign against Moses.  I cannot imagine how difficult it must have been to endure the grumbling and complaining of millions of people thirsty and irritated.  They looked at the water and it probably looked inviting but when they tasted it; it was overwhelmingly bitter.   Undoubtedly they bathed in it, but they couldn’t drink it.  After this went on for a while, the complaint campaign escalated in earnest.  Moses then knew he had to talk to God.
Moses had no solution.  Bitterness is impossible to overcome. God had always provided an escape.  Would He do it again this time?  He showed Moses the remedy for the situation.  He showed Moses a tree to be cut down and cast into the water.
This story is a metaphor, I was told years ago.  The waters are a symbol for life in this world.  The waters were bitter and life in this world is bitter for those who do not know Christ.  In the middle of the bitterness, the Israelites cried out to the Lord for a solution.  He is so rich toward us that He always gives us what we need.  He showed Moses a tree that was to be thrown into the water.   The tree is a symbol for Christ.
By obedience, the BITTERNESS was taken from the water making it sweet.   Life in darkness is bitter, no joy, no peace – but God who is rich in mercy, hears us and gave us His son.  What He gave was beyond our comprehension.   He was slain for our good, He is the answer to our prayers.