As we know, Chazal instituted the weekly reading of the "haftara," a selected reading from the Prophets that corresponds to the week's Torah reading. Generally, the relationship between the Torah reading and the haftara is obvious, though in some instances it is less clear or somewhat tenuous. The haftara for Parashat Vayera (taken from Melakhim II 4:1-37) appears to fall into the first category of haftarot, those with a self-evident connection to the corresponding Torah portion. The birth of a son by the heretofore infertile Shunamite woman quite clearly parallels the highlight of Parashat Vayera, the miraculous birth of Yitzchak to his elderly parents. However, the common practice we follow is to begin this lengthy haftara with the briefer, preceding story about the destitute woman whose creditor prepares to take her sons as slaves since she cannot make her payments. The prophet Elisha miraculously has her tiny oil stock multiply, allowing her to sell the oil and pay her debts. Of what relevance is this story to Parashat Vayera?
It has been suggested that our reading of this story this Shabbat focuses not on the miracle per se, but rather on the insensitive, heartless creditor who has no compassion for the poor widow. He knows that she has no husband - which in ancient times usually meant no means of support - and has only her sons. Losing them would mean losing everything she had in the world. Yet, he refuses to bend and forego - even temporarily - on the money owed to him. He follows the strict letter of the law, rather than exercising a degree of compassion and flexibility towards an impoverished widow.
This conduct directly corresponds to another prominent feature of Parashat Vayera: the destruction of Sedom. Many commentators ask why specifically this city deserved annihilation, while many other societies were also plagued by corruption. The Maharal explains that Sedom's sin lay in their unwavering adherence to strict legality and refusal to bend. The mishna in Pirkei Avot attribute to Sedom the ideology of, "What's mine is mine, and what's yours is yours." They exhibited absolute heartlessness towards the needy, adamantly advocating the rights of each individual to his own money, to the point where sharing was seen as inappropriate and worthy of condemnation. Therefore, God, too, acted towards them with similar inflexibility, denying them access to the divine attribute of mercy. Rabbeinu Bechayei explains along similar lines, noting that no other nation in the world frowns upon charitable causes, sharing one's wealth with others. The story of the poor woman thus brings to mind the sad story of Sedom, the corrosive effects of overly exacting application of the law, such that it leaves no room for mercy and compassion.
Just as the story of Sedom appears in contradistinction to the hospitality and kindness of Avraham Avinu, so does the first half of the haftara stand in contrast with the second story - the Shunamite woman. She and her husband provide lodging and hospitality for the prophet Elisha, on account of which they earned the miraculous birth of their son. Both the parasha and the haftara, then, underscore the stark contrast between the value of "chesed," sensitivity and loving kindness to others, and the quality of Sedom, whereby strict law overrides basic human compassion and consideration.
(Based in part on an article by Rav Amnon Bazak of Yeshivat Har Etzion)