After passing safely through the Red Sea, the children of Israel burst into song. Here is one of their verses of praise:
"The LORD is my strength and song, and he is become my salvation: he is my God, and I will prepare him an habitation; my father's God, and I will exalt him" (15:2).
Only three days later, they had forgotten the parting of the water of the Red Sea because they were out of water and were thirsty. Their song had turned sour. They were murmuring (complaining) against Moses, the man chosen of God to be their leader.
There was water at Marah but it was bitter and undrinkable. Having been delivered from slavery, they had expected smooth sailing throughout their journey. Not so. Here they were with parched throats and nothing but bitter water, the sight of which teased their thirst.
Interestingly, the bitter waters of Marah were encountered directly in the path of God's leading. Some think that trouble always indicates being out of the will of God but that simply is not true. There are some bitter waters along the way in this wilderness journey and God's people are not always detoured around them: "In the world ye shall have tribulation..." (John 16:33).
Bitter waters are not serious unless they make us bitter.
The remedy for the bitter waters of Marah was found in a tree. Moses cast the tree into the waters and they were made sweet. This miracle speaks of the power of the message of the cross to sweeten the bitter waters of life. The Christ of the cross will make your song return.