Bereishit (18:1), “To him appeared HaShem in the plains of Mamrei, and he was sitting at the opening of the tent in the heat of the day.” Ohr HaHaim comments that Abraham became a chariot for the Shechinah. Abraham had received a ה to his name and circumcised, so he was now complete in name and body. “To him…” (of Bereishit 18:1) reflects this higher level, as Bereishit (17:1) states, “And HaShem appeared to Abram and said to him, I am El Shdi, walk before me and become complete. (17:2) I will set my covenant between Me and You…. (17:4) As for Me, this is My covenant with you…. (17:5) Your name shall no longer be Abram, but your name shall be Abraham…. (17:9) …as for you, you shall keep My covenant… every male among you shall be circumcised.”
Nedarim (38a) states that HaShem settles the Shechinah upon one who is strong, rich, wise, and humble. Shabbat (92a), however, gives these qualities: wise, strong, rich, and tall. Tall and humble coincide, as Shmuel (1:10:21) states, “And Shaul son of Kish was chosen, and they searched for him, but he was not found. (1:10:22) And they asked again of HaShem… and HaShem said, he is hiding among the vessels. (1:10:23) And they hurried and took him from there, and he stood in the midst of the people, and he was taller than all of the people from his shoulders upward.” Shaul was tall on the outside, but humble on the inside.
The other qualities also carry a second meaning, as Avot (4:1) states, “Ben Zomah says, who is wise, he who learns from every man…; who is strong, he who captures his inclination…; who is rich, he who is happy with his lot.”
Bereishit (18:1) conveys that Abraham had all the inner qualities. He had strength: he defeated the inclination to stay out of the heat of the day. He was happy with his lot: he wanted to share it with others. He was humble: he searched for any type of guest. He was wise according to Tamid (32a) to sense the unfolding: he realized that sitting in his house that day would bring him no guests. Ben Zomah says that a wise man learns from all men. Bereishit (18:1) therefore states, “…in the plains of Mamrei.” Rashi comments that Mamrei is mentioned because he gave Abraham advice about the circumcision.