Simply replace the unfilled areas such as "" and "[date]" with your information.
Our organization is considering [Employee Name] for a [position title] position within our firm. In [His/Her] employment application, [he/she] identified you as a professional reference.
I would appreciate it if you could share your professional opinion of [his/her] professional performance, strengths, and weaknesses. If would also be of great assistance if you could provide me with [additional required information]. We are specifically interested in [his/her] aptitudes in [additional relevant skills], along with any additional information you feel is pertinent.
As [Employee Name]'s application status will remain pending until the background check is complete, I thank you in advance for your prompt reply. Please feel free to contact me should you have any questions or comments.