Why did Sai Baba's fondness for lighting lamps eventually lead to a conflict with the local merchants?

Sai Baba had a great fondness for the festival of lights and made it a routine to light lamps in the temple and mosque. As detailed in Chapter 5, his method for this involved taking a tin pot and going to the shops of grocers and oil-merchants to personally beg for oil. While this worked for some time, the conflict arose because he did this every day, seeking oil for free. Eventually, the grocers got a 'wicked idea' in their minds, viewing his daily requests as a nuisance that needed to stop, which led them to conspire and refuse his request.