In a moment of extreme distress, a widow faces the threat of losing her children to creditors. The prophet seeks to help her, but he requires a physical starting point, no matter how small, to set the salvation in motion. The primary approach among commentators is that Divine blessing cannot rest on a complete void. It is the practice of prophets to base a miracle on something already in a person's possession, rather than creating something out of nothing [מצודת דוד, מלבי״ם, ביאור שטיינזלץ, אברבנאל].
The woman's admission that she has nothing in her home highlights her absolute poverty. She had been forced to sell all her belongings before the creditors arrived to take her children as slaves [מצודת דוד, ביאור שטיינזלץ]. At the same time, this response is seen as a reflection of the righteous, who willingly let go of worldly possessions and feel they lack nothing even when they own no property [נחל שורק]. Ultimately, the only item she has left is a small jug of oil used for anointing [רלב״ג, רד״ק, ביאור שטיינזלץ].
The resulting miracle unfolded in a continuous, wondrous manner. Because the event was meant to happen all at once, the widow was instructed to gather many empty vessels in advance. As she emptied the small jug she owned, the air entering the vessel miraculously transformed into oil, much like the earlier miracle of a wooden staff turning into a snake. This allowed her to pour an unbroken stream until every available vessel was full [רלב״ג, אברבנאל].
The choice to perform this miracle specifically with oil carries rich historical and symbolic weight. The woman's husband, Obadiah, had faithfully provided oil to illuminate the cave where he hid prophets from danger. It was only fitting that her salvation arrived through oil as a measure-for-measure reward [מלבי״ם]. Additionally, this event parallels the miracle of the oil jug performed by the prophet Elijah for the widow of Zarephath. Since Elisha asked for a double portion of Elijah's spirit, he brought about an even greater wonder. While Elijah's oil replenished a little bit each day, Elisha's oil multiplied in a massive, single outpouring that never depleted [אברבנאל, אהבת יהונתן]. Finally, olive oil represents the power of memory. It serves to emphasize how the sons earned an open miracle and a continuous legacy, even though their father had previously been forced to borrow money with interest to fulfill the will of God [אהבת יהונתן].