Avraham & Sara are forced to leave Canaan and go down to Egypt
because there is a famine in Canaan. When they leave Egypt to go
back to Canaan the verse says:
3 And he went on his journeys from the South even to Beth-el, unto the
place where his tent had been at the beginning, between Beth-el and Ai;
Avraham continued on his travels:
Rashi has 2 explanation on the verse  And he went on his
journeys
First Rashi quotes Masechet Arachin 16:b
Rav Yehuda says that Rav says: From where in the Torah is it derived
that a person should not change his place of lodging? As it is stated
when Avraham returned from Egypt: “And he went on his journeys from the
South to Beth El, to the place where his tent had been at the beginning,
between Beth El and Ai” (Genesis 13:3). Avraham took pains to revisit the
same places he had stayed on his journey to Egypt.
The emphasis, Rashi says, is that even though Avraham was poor when he
went to Egypt and on the way back when he was a very rich man, he
stopped at the same places. Avraham did not let the money get to him and
he stayed at the very same hotel.
Second Rashi – He quotes the Midrash in Berashit Raba when Avraham
returned from Egypt
.רש”י אומר שכאשר אברהם שב ממצרים הוא פרע את הקפותיו
Rashi – Avraham paid back his deaths.
When Avraham went down to Egypt He was poor, he had only troubles and
pains, he was exiled and wandering from his home, with hunger and
sorrow. BUT when he became rich and famous and honorable he did not
forget the people who helped him along the way and stopped at each hotel
he had stayed in and immediately paid them back with a big tip as well.
Rav Zalman Sorotzkin, who passed away in 1966, asks a very powerful
question on the second explanation of Rashi from the book לתורה אזנים.
When Avraham left Eretz Canaan he was very poor, he was a traveler and
no one knew him, so who would lend him money? The Midrash makes a
point to let us know that Avraham paid them back. So who lent Avraham
money and why?
Says Rabbi Sorotzkin, when Avraham went down to Egypt, it’s painful to
say, but Avraham made a השם חילול He Desecrated God’s Name. Of
course not intentionally, but unfortunately as he traveled down to Egypt,
broke people would ask him if your God who you say created the world and
he is the only God and a great God, why can’t you make a living? Why
doesn’t your God help you? Your God Avraham who told you to leave
Charan and go to Canaan and He brings famine to the world and now you
have to borrow money from strangers!?
How could that be?
So when Avraham did become rich in Egypt, he went back to the same
people, to the very same hotels, the same people that lent him money and
saw that he was poor and hungry. “Now look”, Avraham tells them, “You
must trust in God and when you do the reward is heavenly!”
This teaches us that Hashem rewards those who trust him, those who
follow him, and those who are devoted to him. This is what Avraham so of
speak paid back to them, to all the people who asked him all these
questions about his God. He owed it to them and to Hashem, not for his
own Kavod/Honor but to Hashem’s Honor.

By Rabbi Yamin Goldsmith of Beni Brak