We would like to express our gratitude for referring our company, [company name] to [name]. We are grateful for your help in spreading the good word of our service to new customers. Hopefully, in time we would be able to return the favor. We guarantee that we would do nothing to tarnish your name or shame you for introducing us. We would take utmost care of [name].
We hope that our good relationship with you continues to deepen and flourish.