The Gemara brings: anyone who makes himself a מקום קבוע, permanent place, to daven, the G-d of Avraham will be at his assistance… as it states in our parsha “וישכם אברהם בבקר אל המקום אשר עמד שם את פני ה’, and Avraham arose early in the morning to the place which he stood before Hashem.” The word עמידה refers to davening as it states “ויעמוד פינחס ויפלל and Pinchas stood and davened.” What davening does the passuk about Avraham refer to? And where do we find that Avraham always davened in the same place?
The passuk states “and the men (referring to the angels) turned from there and they went to Sedom, ואברהם עודנו עומד לפני ה’ and Avraham was still standing before Hashem.” Onkelos translates עודנו עומד that “Avraham was until now serving Hashem by davening before Him.” The Ramban explains that once Hashem told Avraham the possibility of destroying Sedom, he immediately started davening to save them. The angels left to go to Sedom, and Avraham understood that his davening was not accepted, yet he still continued to daven.
The Seforno adds that even after the angels reached Sedom, Avraham did not lose hope; rather he continued to daven, seeking mercy and searching for a merit to save them. This is as Chazal say “even if a sharpened sword is placed upon a person’s neck he should not hold back from davening.” The passuk states ויגש אברהם, Avraham then came close and davened, “האף תספה צדיק עם רשע.” Rashi explains the word אף as גם-also, “Will you also destroy a tzaddik with a rasha?” Onkelos translates the word אף as כעס-anger, “Will Your anger convince You to destroy a tzaddik with a rasha?” All of this shows that Avraham davened as much as he could to save Sedom.
The passuk states that the next morning Avraham went אל המקום אשר עמד שם את פני ה’ which Onkelos translates as, “To the place where Avraham davened” to save Sedom. This shows that Avraham continued davening in the same permanent place as the day before, even though Hashem did not accept his tefillah.
Why do we find specifically by Avraham the inyan of davening more than by anyone else in the Torah? Avraham recognized Hashem as the creator of the world, believed in Hashem completely and taught everyone about Him. Avraham understood that Hashem Who creates a difficult situation can certainly enable it to be resolved. Therefore we find by Avraham his continuous davening to Hashem.
Another answer is that Avraham who was the epitome of chessed, did chessed by davening for people.
May we learn from Avraham Avinu to daven to Hashem in a מקום קבוע and to do the chessed of davening for other people.