Right from the beginning, the children of Israel were a people of unbelief. Though from time to time they show glimpses of faith (Ex 4:31; 15:19-21), their overall pattern was one of unbelief and testing the Lord. The Lord intended to use them to make known his might and power, and to get glory through the people of Israel. It was for this reason that he would bring them into the position of near destruction or great calamity. With his working in this way, putting the people in the place of utmost duress and unfathomable escape, he would leave no doubt that he was at work, and he was the one saving them. Yet, even when he clearly laid out his plan for them (Ex 4:21-31; 14:1-4), the people would shrink back in unbelief, refusing to believe his promise (Ex 5:20-21; 14:10-12).
The people went into wilderness of Shur (Ex 15:22ff) after the Lord had “triumphed gloriously” by leading them through the Red Sea and destroying Pharaoh and his minions. After three days they were unable to find water to drink. Soon they stumbled onto a spring, but the water there was bitter. Here again they doubted the Lord, and murmured against Moses about the lack of good water. The people pejoratively nicknamed the place “Marah,” they were so upset about the situation. Moses, of course, prayed and followed the instructions of the Lord in cutting down a nearby tree and throwing it into the water, thereby making it “sweet.”
What we usually find astonishing in this passage is the fact that the people complained in so short an amount of time after being delivered so gloriously by the Lord through the Red Sea waters. Perhaps a short amount of reflection would remind us of how quickly we begin complaining. The Lord is indeed longsuffering to us in our infidelity.
After this incident, the narrative continues,
There the LORD made for them a statute and a rule, and there he tested them, saying, “If you will diligently listen to the voice of the LORD your God, and do that which is right in his eyes, and give ear to his commandments and keep all his statutes, I will put none of the diseases on you that I put on the Egyptians, for I am the LORD, your healer.” (Ex 15:25b-26 ESV)
The point is that the Lord can and should be trusted. This sort of doubting will not do. The one who was faithful in saving the people out of Egypt and through the Red Sea could be trusted to provide for them in their pilgrimage to the promised Rest. Just as Moses, by keeping the Lord’s instruction, made the bitter waters of Marah sweet, so the children of Israel, in keeping the Lord’s instruction to them, would make life sweet. To demonstrate further his point, the Lord then leads them (the passage does not explicitly say the Lord led them on to Elim, but we know the cloud and fire were already at work [Ex 13:17-22]). Here, Moses remembers, “were twelve springs of water and seventy palm trees.” By these waters the people encamped.
The Lord knew what was going on Marah. He knew that Elim was right around the corner. The people did not, and so they doubted and were unbelieving. Little did they know how much God had in store for them. Something far better than a measly pool–twelve springs of water and seventy palm trees. The Lord had no intention of punishing them the way he did the Egyptians. As long as they kept his statutes, he intended on being their healer, and caring for the people. Their responsibility was to wait for their salvation that he would inevitably bring. Even while they were still complaining, the Lord knew that the paradise was only a short distance away.