Avrohom Avinu was the greatest host there could be and he would make these extravagant meals for all types of people as we see by the Melochim tounge and mustard sandwiches and cakes and butter and only a little bit of water...WHOH!!- only a little bit of water?!?! Why was he so cheap on the water? Everything else was in great abundance- of all things water?!?!?!?
R' Yisrael Salanter answers beautifully-
He was once passing through a small town and stopped with his friend to daven Mincha, when his friend washed his hands, he washed with alot of water as usual, but when R' Yisrael washed he only used a little bit, and he explained that this is a small shul and the Gabbai probably only brought enough for the amount of people that always come so why should he make the Gabbai go get more. So it was by Avrohom- all the food and delicacies HE brought in great abundance but the water that he asked Yishmael to bring and at someone else's expense he was'nt going to need alot and make Yishmael carry more water, even for Hachnasos Archim which was so dear to him!! He had his priorities straight!!