My mom is a firm believer in giving a "cup of cold water" for the sake of the Kingdom. From my youth, I have multiple images in my head of sitting in a church service thinking the pastor was getting a bit slow and boring when in fact, as my mother realized, he was simply tired and thirsty. Whether or not anyone else in the congregation caught on, I feel that I will never know; but I do know that my mother was the only one that ever acted on her insight as she got up quietly in the middle of service and got the man some water.
One of my favorite Bible stories is only three verses long. In Exodus 17, the children of Israel have not only left Egypt, but they have crossed the Red Sea, sung of victory, had bitter water made sweet, received bread from heaven and water from a rock. Interspersed among it all was much complaint about hunger and thirst, and whining about dying in the barren, forsaken wilderness. The one man who led Israel through all of it, who petitioned God for daily sustenance, and had been the recipient of thousands of complaints, now has to lead his people into battle against Amalek. Moses is tired, no, he is exhausted, weary, worn, malnourished, over-worked, with little sleep and fewer benefits. But he continues on because he knows Joshua needs his encouragement and the children of Israel need to see God's hand mightily at work.
With all this in mind, Moses takes his place at the top of a hill overlooking the battle, but chapter 17 makes very clear that he is not alone:
Most leaders, most mentors, hide their pain and weariness from public spectacle. Aaron and Hur had a long history of intentional living and involved interaction with Moses that lead them to the insight that he needed them at this one moment more than ever before. The lessons of discipleship are wrapped up in this one story. Aaron and Hur knew Moses enough to know what he needed, they acted on their insight and provided what they could, then they stuck with Moses, seeing the battle through to the end. The cup of cold water, or the need of the moment in this case was a stone to sit on, while the intercessory act of holding up Moses' hands was the fruit of his faithful and intentional discipleship all along the way.