Exodus 15:23-25

21st Century King James Version

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 [that is, Bitterness].

²⁴ And the people murmured against Moses, saying, “What shall we drink?”

²⁵ And he cried unto the Lord; and the Lord showed 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 put them to the proof,