My father, the Kretchnifer Rebbe shlita (Gilyon Divrei Torah) notes that Avrohom served Hashem in Eretz Yisroel through the mitzvah of hachnasas orchim. In this way, he drew people close to Hashem. We may ask why he specifically chose to bring people to Hashem through eating and drinking, rather than through words of Torah and mussar.
He answers with the following story:
When the Sanzer Rov zy”a was in Vienna, his tish was attended by very simple people. One of them was very far from Torah and mitzvah observance, and he often ate non-kosher food. At the tish, the Rov called him over and gave him some “shirayim”. After the man ate the Rov’s shirayim, he began to vomit. He threw up everything he ate that day. From then on, his body could not tolerate any of the food he ate and he was constantly vomiting. After a while, he was very sick and seemed to be at death’s door.
The man was brought to the Rov, who told him what he must do. He said that from then on, he should only eat kosher food. He explained that since his body had ingested holy food, it could no longer tolerate treif food, and it would expel any non-kosher food he tried to eat.
It is certain that the same was true of the people who ate in Avrohom’s house. After eating his holy food, their bodies could no longer tolerate non-kosher food. In this way, Avrohom made them holy and brought them close to Hashem.
