Exodus 15:23-25

Young's Literal Translation

²³ and they come in to Marah, and have not been able to drink the waters of Marah, for they [are] bitter; therefore hath [one] called its name Marah.

²⁴ And the people murmur against Moses, saying, `What do we drink?'

²⁵ and he crieth unto Jehovah, and Jehovah sheweth him a tree, and he casteth unto the waters, and the waters become sweet. There He hath made for them a statute, and an ordinance, and there He hath tried them,