Can you explain the story of how Sai Baba lit the lamps with water? What led up to it?

According to Chapter 5, Sai Baba had a great fondness for lighting lamps in the temple and the mosque. He would personally go to local grocers and oil-merchants every day to beg for oil. After some time, the grocers conspired to stop giving him free oil. When they all refused him one day, Baba returned quietly to the mosque. He took his tin pot, which contained a minuscule amount of oil, poured water into it, drank the mixture as an offering, and then filled the lamps with plain water. He then lit the water-soaked wicks, and miraculously, they burned brightly all through the night. This event amazed the grocers, who realized the power of Baba and repented for their actions.