Can you explain the story of how Sai Baba lit the lamps with water when the shopkeepers refused to give him oil?

According to the account in Chapter 5, Sai Baba had a great love for lighting lamps and would daily collect oil from local shopkeepers. One day, the grocers conspired to refuse him. When they all said "no," Baba calmly returned to the mosque. He took his tin pot, which had a minuscule amount of oil, added water to it, and drank the mixture as an offering. He then filled the lamps with plain water and lit the wicks. To the amazement of the watching grocers, the lamps burned brightly all night long, demonstrating his divine power in a stunning miracle.