יקח נא מעט מים (וירא יח:ד)

Rashi says that Avraham sent a servant to bring water.

The congregants of the Beis Medrash where Reb Yisroel Salanter zt” once noticed that when everyone washed their hands before davening (as halacha dictates), Reb Yisroel Salanter only took a little water to wash his hands, unlike everyone else who filled up a complete cup to wash.  They wondered at his behavior and asked him about it, to which Reb Yisroel Salanter answered: 

As you all know, Avraham Avinu was the most incredible host. He served plenty of everything, but when it came to serving water, we read in the Torah: “יקח נא מעט מים.” This begs the question: why did Avraham ask for just a little water? The answer is as follows: Avraham taught us that whenever one fulfills a mitzvah, it should be done to perfection.  Not so with the water, which means that a servant has to lug it from the river or the well. 

Reb Yisroel finished, “The Shamash – caretaker – works very hard to draw water from the well, and when the water is used up, he has to fetch more water. If my water is on his account, then a little water is fine for me!”. Moral of the story: Do not be frum on another person’s account of someone else!