Vayeira

On the third day after Avraham gave himself a bris, Hashem, in order that Avraham not be bothered, caused a great heat so that there would be no travelers for Avraham to host. Avraham whose very essence was kindness, was not at all happy about that and was looking out for people that he could help.  Hashem, seeing that Abraham's emotional pain was greater than his physical pain, had three angels that looked like travelers, pass by his tent so that he could host them. 

Avraham sees the angels, runs to them, asks them to stay and says יקח נא מעט מים ורחצו רגליכם, "Let some water be brought, please wash your feet," and ואקחה פת לחם, "I will bring some bread." Rav Shach notes that the Gemara tells us that Avraham went and slaughtered three cows so that he could give each of the three guests the choicest part of the animal. We see that he spared no expense in treating his guests, so Rav Shach asks, why when Avraham said bring water, he said just bring a little? 

He answered with a story. Once, when Reb Yisroel Salanter went to one of his students for a meal, he went to wash his hands. Since at that time they didn't have running water, they had a butler who would have to go to the well, draw the water and bring it to the house. The student saw that his Rebbi was using very minimal water to wash his hands. The student, alluding to the Gemara that says if you use a lot of water to wash for bread you will have abundance and blessing from heaven asked jokingly, "Doesn't the rabbi want to become wealthy?” The rabbi answered, “I don't want to get rich on the back of the butler; he shouldn't have to work harder so I can get bracha."

The Gemara also tells us that whatever Avraham did for the guests himself, Hashem paid back his children himself, and whatever Avraham did with a helper Hashem paid back with a helper. The Torah tells us that Avraham ran to the cattle himself, so Hashem himself brought the Jews meat in the desert. However, the water that Avraham brought by way of a messenger, Hashem sent the Jews water in the desert by way of a messenger. Moshe had to get water from the rock, Hashem didn't give it himself.

So, says Rav Shach, what Avraham did himself, like the cattle, he didn't skimp at all and brought them each the best cut from their own cow. However, the water that he had someone else bring, he said to bring a little, for even a mitzva he didn't want to do in the best way, if it was going to affect someone else. 

It would seem though, that he was punished for this since Hashem didn't give the Jews the water Himself. What did he do wrong? He had his son bring the water to teach him to do mitzvos; why would he be punished? The sefer בני שלמה says that had Moshe brought the Jews into Israel, then the Bais Hamikdash never could have been destroyed. If that were the case, when the Jews sinned, there would have been no hope for them, for then they would have been destroyed. Now, when they sinned, Hashem took out his anger on the Bais Hamikdash and destroyed it instead of the people. 

What caused Moshe not to be able to go into the land? It was because he hit the rock to get water for the people. Now if Hashem Himself had given the water, Moshe wouldn't have hit the rock and he would have gone into the land. It turns out that that would have been the worst thing for the Jews. This shows us that Avraham did the right thing by sending the water with his son, even though then he had to give less. This teaches how careful we must be even when doing mitzvos, not to do them in a way that's going to affect other people. As Reb Yisroel said, “not of the back of the Butler." However, what you can do yourself, do the best you can!