A Joyful Song of Praise—to Complaining
After watching the Eternal miraculously putting a final end to the Egyptian army, the Israelites were in a state of elation. A song was composed by Moses and sung by the multitude in grateful appreciation for God's deliverance. Miriam, the older sister of Moses and a prophetess, led the women in dancing with timbrels, a type of tambourine. If only the chapter would end with this happy event. But it was time to move on, and three days passed without a water source being found. Their reserves had been depleted and many were very thirsty.
In the arid climate of the region, people and animals alike needed much water every day. Water could be stored in animal skins, which would "sweat." When the dry wind passed over the skin, it would have a cooling or chilling effect on the stored water. But with millions of people and animals, a large supply of water was essential. Do we find the people crying out to God for their needs—the One who had saved them and had met all their needs thus far?
Sadly, only a few days have passed since the wondrous event at the Red Sea and we find the Israelites once again complaining before Moses. On their arrival at an oasis called "Marah," named so because of the bitter water, God again used a miracle to teach the Israelites a lesson. As God in His mercy miraculously purified the bitter waters despite their complaining, He also made a covenant with the Israelites. As long as they trusted in and obeyed Him, He would also be their Healer. The sicknesses and diseases that they had seen befall the Egyptians as a result of ignorance, disregard and disobedience to God's righteous laws would not afflict the Israelites.
A part of God's promise to Israel that they would escape disease and illness involved their obeying the many statutes He gave them that pertained to physical health. Numerous health principles that God gave through Moses are scattered throughout the Pentateuch. They involved public hygiene, water supply, sewage disposal, proper diet and control of infectious disease. Since God gave so much detailed instruction in these areas, it may imply that Israel was not living according to God's health code in Egypt. Medical doctors S.I. McMillen and David E. Stern wrote in their book, None Of These Diseases: The Bible's Health Secrets for the 21st Century (2000, pp. 9-11), that Egyptian medical and sanitation practices were abominable. There is a lesson for us in this. God wants us to be healthy and He is also our healer. However, if we do not live in accordance with what we know to be sound health principles today, we are not doing what we can to maintain good health, and we may suffer disease as a result. God expects us to live wisely and do what we can to sustain good health.
When the Israelites arrived at another oasis, called Elim, we find that each tribe had a well provided for it. We also read that there were 70 palm trees there, which, interestingly, was later the number of the elders of Israel (Numbers 11:24-25 Numbers 11:24-25  And Moses went out, and told the people the words of the LORD, and gathered the seventy men of the elders of the people, and set them round about the tabernacle.
 And the LORD came down in a cloud, and spoke to him, and took of the spirit that was on him, and gave it to the seventy elders: and it came to pass, that, when the spirit rested on them, they prophesied, and did not cease.
American King James Version×).
Supplementary Reading: "Miriam: A Lifetime of Faith," The Good News, May—June 1997, pp. 25-27.