(Exodus 15:24-25)

24 And the people murmured against Moses, saying, What shall we drink? 25 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, (Moses prayed to God in very short words, but it was a great prayer)