Exodus 15:23
“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.”
And Miriam answered them, Sing ye to the Lord, for he hath triumphed gloriously; the horse and his rider hath he thrown into the sea.
So 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.
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.
And the people murmured against Moses, saying, What shall we drink?
And 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,
Counter-Arguments
The strongest case that this verse does not belong in this theme.

Related Verses
“And 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,”
“And the people murmured against Moses, saying, What shall we drink?”
“And he called the name of the place Massah, and Meribah, because of the chiding of the children of Israel, and because they tempted the Lord, saying, Is the Lord among us, or not?”
“This is the water of Meribah; because the children of Israel strove with the Lord, and he was sanctified in them.”
“And the people thirsted there for water; and the people murmured against Moses, and said, Wherefore is this that thou hast brought us up out of Egypt, to kill us and our children and our cattle with thirst?”