Can you explain the miracle where Sai Baba supposedly lit lamps using water instead of oil?

According to the account in Chapter 5, Sai Baba had a great love for lighting lamps in the mosque and would daily beg for oil from local shopkeepers. One day, the grocers conspired to stop this "nuisance" and refused to give him any. In response, Baba took his tin pot, which had a tiny bit of oil, added water to it, and drank it as an offering. He then filled the lamps with plain water and lit them. To the amazement of the grocers, the lamps burned brightly all night long without any oil, a miracle which made them feel deep repentance for having lied to him.