Exodus 15:25

The Lord shewed him a tree. The name of this tree is not revealed. Several trees or plants belonging to different parts of the world are said to possess the quality of rendering bitter water sweet, but none of these have been found on the Sinai Peninsula. In fact, the Bedouins of the neighborhood, who consider the water of the ‘Ain Hawarah and other similar springs in the vicinity unpalatable, know of no means by which this water can be made drinkable. Hence there are but two possible explanations for this text. Moses was either directed to take a tree which had the natural quality of changing bitter water into sweet, which tree no longer grows in that area, or the transformation of the water was a direct act of God and the tree was only of symbolic significance.

An ordinance. After healing the water and satisfying the physical thirst of His people, God gave them an ordinance that was connected with the miracle by a promise (see v. 26).

There he proved them. From the time of their departure from Egypt to their entry into Canaan, God “proved” His people on many occasions — first at the Red Sea, now at Marah, later at Meribah (ch. 17:1-7), Sinai (ch. 20:20), Taberah (Num. 11:1—3), Kibroth-hattaavah (Num. 11:34), Kadesh (Num. 13:26-33), and elsewhere. These “proofs” were part of God’s attempts to train them, under comparatively easy circumstances, for the experiences they would face in Canaan.