Chayei Sarah 5778

At the beginning of the parsha, we read about Avraham buying the Cave of Machpela from Efron and the Hittites. At first, they offer him free passage to the cave without any kind of fee; but Avraham insists to pay for the cave and its field. This isn't the first time Avraham turns down gifts from others. In Lech Lecha, he turns down the offer of the king of Sodom that he would take the captives while Avraham takes their property. Avraham refuses so that no one would say that the king made him rich. This can be based on the verse from Proverbs (15:27): "The greedy ruin their house, but the one who hates gifts shall live." Avraham lived by these words and made sure not to be accustomed to getting things for free; he did not want to create a mindset of entitlement.
There is another understanding of these two stories, and Avraham shows us the midpoint between two extremes. In regards to the story with the king of Sodom, Avraham turns down the offer to show that everything in this world is from Hashem. You might receive gifts and items from people, but in essence you received it all from Hashem. Avraham wanted to get that point across to the masses as well as show that he was happy with what he had. When Avraham buys the cave, he shows that he's willing to put in effort to attain things. He's not expecting miracles to happen and everything he needs will just fall right out of the sky.
The two extremes are how one views his/her effort and G-d's part in it. One extreme is saying everything is from G-d and therefore one can sit back and wait for things to happen. The other extreme is putting in effort into everything, but forgetting G-d in the process (a sense of pride that *you* did everything yourself with no divine help). Avraham finds the balance between the two. He knows everything is from G-d, yet he continues to put effort into everything he does.
A good example is bread. For months, a person plows his field, grows wheat, harvests it, grinds it into flour, kneads it into a dough, and bakes it. When he finally sits down to eat it, he says a blessing: Blessed are You, G-d, Who has taken bread out of the ground." But he just did everything himself! Why is he attributing it all to G-d? Because that's exactly it; he is thanking G-d for giving him the ability to make the bread and for the natural processes for taking place.

Vayeira 5778

Why were the cities of Sodom and Amorrah severely punished to the point of total annihilation? The Ramban answers because they were situated within the borders of Eretz Yisroel, and the land could not tolerate their wickedness. It is written in Parshas Kedoshim and Acharei Mos that the land spits out those who don't maintain the sanctity of area. Because they were the most evil of people who despised others as well as G-d, they were completely uprooted and destroyed to the point that the land could never sustain another city there again. G-d then used these cities as examples for Bnei Yisroel in Parshas Nitzavim (29:22), saying this will be their fate for not keeping the Torah.