This is the quotation of customer famous in the name of Gandhiji.

But there is no source anywhere in his writing in 100 volumes of collected works.

A Customer is the most important visitor on our premises.
He is not dependent on us.
We are dependent on him.
He is not an interruption on our work.
He is the purpose of it.
He is not an outsider on our business.
He is a part of it.
We are not doing him a favour by serving him.
He is doing us a favour by giving us an opportunity to do so.