Why did the shopkeepers refuse to give Baba oil, and how did they react when he lit the lamps with water?

As described in Chapter 5, the shopkeepers decided to stop giving Sai Baba oil because he came to get it for free every day, and they considered it a nuisance. They conspired together to refuse him. However, after they denied him oil, they watched as Baba proceeded to light the lamps using only water. Seeing the water-fueled lamps burn brightly all night, the grocers were utterly amazed, putting their fingers in their mouths in astonishment. They felt deep repentance, realizing they had sinned by lying to Baba and causing him trouble, and they began to tremble with fear and regret.