In Parshat Lech Lecha, we see many midot of Avraham. One midah that repeats itself throughout the parsha is the midah of dealing with wealth and understanding where it comes from.

When Avraham and Sarah go to Egypt, Avraham says to Sarah, "Please say that you are my sister so that they will favor me because of you." Rashi says that Avraham thought the Egyptians would give him gifts. The Zohar similarly says that since one acquires wealth through the merit of his wife, Avraham thought he would accumulate wealth from other nations through the merit of Sarah. It seems strange though that in middle of a life threatening matter that Avraham and Sarah are in that Avraham would be concerned about acquiring wealth. Why would Avraham be worrying about gifts?

The Ramban answers that Avraham was constantly searching for ways to fulfill God's blessing of wealth which was given to him at the beginning of our Parasha. When Avraham and Sarah were forced to go to Egypt because of the famine, Avraham saw it as "the fulfillment of God's blessings."

We see that Avraham does acquire gifts and it says that Avraham leaves Egypt and was "כבד " with livestock, silver and gold. "כבד " is normally used for describing a famine or something negative, so how can one describe wealth with "כבד "? In truth, wealth can be a burden. When someone amasses a lot of money will they use it properly? Will they give tzedakkah? Will they become arrogant? Perhaps even the great Avraham despite being such a Tzadik , had this burden. The Torah adds in the word "כבד " to show us that with wealth comes a heavy burden and that one must be careful with how he uses his money and not get caught up in the materialism.

Later in the parasha the king of S'dom said to Avraham "Give me the people and take the possessions for yourself." Avraham replies saying he won't take a thing from Melech Sodom so that everyone can say that all of his wealth was acquired from Hashem and no one else. Avraham is fully aware that anything he has in this world comes from Hashem. Even though money is such a physical and materialistic thing Avraham makes it into something very holy and spiritual by using it to serve Hashem.