Verses 22-25 “22So Moses brought Israel 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.
23And 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.
24And the people murmured against Moses, saying, What shall we drink?
25And he cried unto the LORD; and the LORD shewed him a tree, which when he had cast into the waters, the waters were made sweet: there he made for them a statute and an ordinance, and there he proved them,”
At Marah the waters were bitter, and the Children of Israel murmured against Moses. To complain about Moses was to complain against God. God was patient with their complaining for a long time; but eventually, their complaining would be judged by God and many of them would die in the wilderness (Num.14:29). God would have us to do all things without murmuring (Phil.2:14). And he warns us, “Neither murmur ye, as some of them also murmured, and were destroyed of the destroyer” (I Cor.10:10). We should not complain against God because He is the only one who can make the bitter things of life sweet. God’s plan for our lives is far better than our own and will result in more sweetness and joy than our own plan.