Israel grumbles at Mara here in Ex. 15; in the next chapter, they grumble in the wilderness of Sin; and in the chapter after that, they grumble at Rephidim. Lord-willing, we will spend a week looking at each one of these episodes. Interestingly, after the people leave Sinai there are three more grumbling episodes in Numbers 14-17. This is not a problem that was easily overcome, and if you have a complaining tongue in your head, you will know that it is not easy to stop. By and large grumbling is not a sin that our congregation is given over to. Thank God — and watch yourself. Gripe sessions are only too common, whether about your spouse, your boss, your parents, your children, your country, your neighbors, or all of the above. And God hates them. He demands that instead of grumbling we obey Him, and when we obey Him, we live in health, fullness, and blessing.