Musar על בבא קמא 184:2

Abraham continued by saying: "I shall take a loaf of bread, etc." We note that he prepared a great deal of bread as proved by the quantity of flour the Torah describes as being used, i.e. three סאים of fine flour. [This is the equivalent of about 432 eggs. Ed.] Since an amount of 3 סאים קמח equals the measure known as איפה, we must ask ourselves why Abraham did not specify that one איפה קמח be used. The reason is that if one measures a particular amount three times, in this case a סאה, the total that one winds up with is liable to be in excess of what one gets when measuring only a single איפה. Our Rabbis describe that little extra amount whenever one measures [so that one does not shortchange the customer] as קלבון. The Torah's point is to draw our attention to Abraham's generous spirit. Interestingly, though a great amount of bread was prepared, we do not read about any of it being served. Rashi, basing himself on Talmudic sources, writes that this was due to Sarah having unexpectedly menstruated while preparing the dough. We will follow a different approach. Seeing that only a small fraction of that amount would be served during that meal, the Torah did not consider such a fraction worth mentioning. Why did Abraham want so much bread to be baked? We can understand why he had to slaughter three oxen if we accept the view expressed in Baba Metzia 86 that he wanted to serve each guest a tongue with mustard. But why would he need so much bread? We must read the sequence as follows "He said: I shall take a loaf of bread and you can refresh yourselves. After that, you may depart." Abraham indicated that the excess bread would be given to them as provisions for the rest of their journey so that they would have refreshments also after having departed from him. This would correspond to the advice of our sages in Pessachim 112: השכם ואכול בקיץ מפני החמה, ובחורף מפני הצינה, "rise early to eat your bread, in the summer because of the heat, and in the winter because of the cold." Since it was very hot at that moment, Abraham provided bread for them to eat when it would be cooler, towards evening.