Dear :

I would like to ask your permission to use your name as reference for our [product/service].

For over years, you have been our valued customer and a respected professional in [area]. This makes you a perfect reference for our business.

I will call you next Monday for a response. If you have any questions, please call me at [phone]. I'm available between [time] and [time].

Sincerely yours,

[name]

[title]