What is the significance of the fact that the kings of S'dom and Amorah "fled, and fell there (in the pits of bitumen)"?
Rashi #1: They fell in pits that resulted from removing the earth for use in building. 1
Rashi #2 (citing a Midrash): They sunk in the bitumen, and it is normally impossible to extricate oneself from there (like quicksand). 2 The Pasuk is teaching us here that a miracle occurred to the king of S'dom. 3 As a result of this miracle, those people who hitherto were skeptical that Avraham had survived the furnace of Ur Kasdim, now believed in that, too. 4
Ramban: Presumably, the two kings were trapped in the bitumen, and a miracle later occurred as Avraham passed by (perhaps he even looked into the wells). Refer to 14:10:1.1:1.
Seforno: The Torah is coming to teach us that Avraham chased after the four kings despite knowing that he could not rely on the kings of Sedom and Amorah to assist him.
Hadar Zekenim: The word "Va'Yipelu" means not that they fell there, but that they camped there. They hid in pits from which they take earth for clay.
Gur Aryeh: This then is why it mentions that they contained Cheimar. According to this first approach, the pits were not necessarily full of bitumen at the time.
Gur Aryeh: Otherwise, why would the Torah need to tell us what the wells contained?
What does "Herah Nasu" mean?
Rashi: Based on the principle that a "Hey" at the end of a word often replaces a "Lamed" at the beginning, "Herah Nasu" means, "they fled [each one] to a mountain."
QUESTIONS ON RASHI
Rashi writes: "'Wells of bitumen' - There were many such wells." How does Rashi derive this?
Gur Aryeh: He derives it from the repeated word, "Be'eros Be'eros [Cheimar]."
Rashi writes: "When the skeptics heard of this miracle, they also believed the miracle of Avraham [being saved from the furnace of Ur Kasdim]." Ramban asks
Ramban: Perhaps the king of S'dom emerged from the well just as Avraham passed by to rescue them and return their possessions, and it was evident that the miracle occurred in Avraham's honor.
Mizrachi: The idolaters did not believe in any deviation from the normal course of nature. When they observed this clear miracle, they began to believe in Avraham's salvation as well, and it was known that the latter was due to Avraham's steadfast conviction in one G-d.
Gur Aryeh: By natural means, the four kings were the strongest. Avraham's victory demonstrated that Hashem was assisting him, and not assisting the king of Sedom, because (a) Sedom was initially defeated; and (b) if the king of Sedom was worthy of a miracle in his own right, he would never have fallen into a pit in the first place. Therefore, all realized that he was saved only in the merit of Avraham.