Why is the word "Aholo" (his, Avraham's, tent) written with a 'Hey' (at the end, i.e. "her tent")?
Rashi: To teach us how Avraham honored his wife, 1 inasmuch as he pitched her tent before he pitched his own.
Moshav Zekenim: It teaches that he made a separate tent for her, for travelers may not have relations.
This is like Chazal said: "one should love one's wife as much as one loves himself, and honor her more than himself." Gur Aryeh cites a source in Chulin 84b.
What is the significance of the fact that Beis-El was on Avraham's west, and Ai on his east?
Seforno: This teaches us that Avraham deliberately settled between two large towns, 1 so that travelers who passed by from either town would hear when he called out in the Name of Hashem (thereby bringing them closer to believing in Hashem). 2
What does the Pasuk mean when it tells us that Avraham called in the Name of Hashem?
Rashi, Targum Onkelus, Targum Yonasan,: It means that he prayed to Hashem. Refer to 12:8:3.1:2.
Ramban: It means that in front of the Mizbe'ach he called out to the Name of Hashem - to encourage the people to believe in Him and worship Him. 1
Chochmah u'Musar (Vol. 4, p.7): This is like one who calls his friend, so he will come. When we call, His name dwells there. All salvations of Yisrael are through calling, and His name comes.
Why did Avraham build another Mizbe'ach?
Rashi: Avraham foresaw that his descendants would sin upon entering Eretz Yisrael (when Achan took the spoils) and he prayed on their behalf.
Ramban: He continued to proclaim the Name of Hashem to all. 1
Why did Avraham pray regarding the tragedy of Ai, more so than the other tragedies that would befall Bnei Yisrael?
Gur Aryeh #1: The location itself was the cause of the revelation of this future event. Refer to 12:6:5.1:2.
Gur Aryeh #2: In 12:7, Hashem informed Avraham that his descendants would be given the Land. Hashem then showed Avraham the manner in which they would receive it, i.e. that not a single person would fall in battle, except at Ai due to the sin of Achan. Therefore, Avraham prayed for them at this point.
QUESTIONS ON RASHI
Rashi writes: "He moved (va'Ya'tek) - his tent." But perhaps the verse means that Avraham moved himself?
Gur Aryeh: The verb "va'Ya'tek" is in the causative (Hif'il) form.
Rashi writes: "... first [Avraham] pitched his wife's tent, and afterwards his own." How do we derive that her tent was first?
Gur Aryeh: We interpret the Kesiv (the way a word is spelled in the Sefer) before the K'ri (the way it is pronounced). 1
Even according to the opinion that we generally interpret the K'ri first (see Tosfos to Chagigah 2a), in this case it would be obvious that Avraham made a tent for his wife at some point; rather, the point must be that he made her tent first.
Rashi writes: "It emerges that Beis-El was to his west." What is Rashi clarifying for us?
Gur Aryeh: We might have misinterpreted the verse to mean, "he traveled from east of Beis-El (mi'Kedem), to the mountain (ha'Harah) [west of Beis-El]." Rather ,the verse means, "to the mountains at the east [side] of Beis-El."
Rashi writes: "... so he prayed for them there." How is this derived from the verse?
Gur Aryeh #1: The verse says, "he built a Mizbe'ach there," specifically, because he wished to pray for them at that location.
Gur Aryeh #2: This verse adds the phrase, "and he called out in the Name of Hashem" (which did not appear in 12:7 regarding the first Mizbe'ach); this teaches that Avraham prayed. 1
Although Avraham had prayed for the sons of Yaakov (Shimon and Levi) at Shechem (see Rashi to 12:6), he did not build a Mizbe'ach along with that prayer, for it was not a prayer for the entire Bnei Yisrael