At the beginning of Parshat Vayera Rashi quotes Rabbi Chama Bar Chanina (Bava Metsiah 86:42) who explains that in the beginning of Parshat Vayera, it was the third day after Avraham’s Brit Milah and Hashem came to find out how he was feeling. The world stands on three pillars: Torah, Avodah, and Gemilut Chasadim. Each one of our forefathers set the standard for each individual pillar. Avraham Avinu set the foundation for Gemilut Chasadim. When we think of Hachnasat Orchim, the first person that comes to mind is Avraham. However, after he had his Brit Milah he was stuck in his bed and could not fulfill the Mitzvah of Hachnasat Orchim. Rabbi Yisrael of Chortkov explains that during these days Avraham was considered “one who thought to fulfill a Mitzvah but could not do so, therefore, was considered as one who did it regardless” (see Kiddushin 40a). For every Mitzvah man fulfills, an angel is created. Avraham’s good will and intention to fulfill the Mitzvah of Hachnasat Orchim for the past three days consumed him. Hashem sent three angels that were created from Avraham’s powerful will and fierce determination to fulfill the Mitzvah. Hashem wished to appease Avraham and demonstrate that through fierce determination and perseverance in fulfilling a Mitzvah, it is considered as if the Mitzvah was indeed fulfilled. With the appearance of the three angels in Avraham’s doorway, we learn that the visit indeed took place on the third day after Avraham’s Brit Milah.