In the Old Testament, after God took the Israelites out of Egypt and after he took them across the Red Sea, they wandered around the desert for three days without water.
Obviously this was concerning. Remember it only takes 3 to 4 days without water to die and this was a large group of people with a lot of livestock who were wandering around the desert. So they were complaining and they failed their first test. If you back up to early in this story, God said that he had heard the cries of his people and he came to rescue Israel out from under the bondage of Egypt however when Moses gets to Egypt it doesn’t seem like there are any practicing Israelites so what did God hear? The Bible doesn’t really say.
When the Israelites came out of Egypt, they didn’t have to do anything for it. Moses came, Moses told them what God was going to do, God did all the miracles, and Egypt kicked them out. There really was no faith on the part of the individual Israelite involved in the whole process. Even as they fled from the Egyptians and crossed the Red Sea it was still God doing everything.
So it was that in the desert for three days they finally had to show whether or not they believed God was their God and whether He was their provider. You see it’s one thing to say you have faith in God, it’s an entirely different thing to do what God says even when it goes against everything in you. Because faith really isn’t faith until you are willing to give up what you feel, what you understand, what you know you need in order to do what God says.