For the past three Motza'ei Shabbatot, we have had shiurim on the topic of Practical Shmita. This does not include those who attended about 10 other shiurim on the topic in Elul. In Kiddush L'vana we quote Rabbi Yishmael as saying that if we had only one opportunity in a month to greet the Sh'china, it would be sufficient. If Hachnasat Orchim were equal, then one act of hospitality a month would suffice. But it isn't.
Hospitality is a constant ongoing mitzva.
That angel is now accompanied by R'fael, whose new task is to save Lot and family. Avraham escorts the angels on their way to S'dom. HaShem next tells Avraham of his intention to destroy S'dom. Avraham pleads and bargains on their behalf, but there aren't enough righteous people to save the cities. Says the Gemara, because of Avraham's humility, his children merited two mitzvot - the ash of the Para Aduma and the dust of the Sota.