Hi,
Welcome to the Forum.
In N. America, this would be called a letter of reference.
Mr. ----- worked for XYZ as an accountant from Dec. 2004 to Dec. 2005.
During his stay at XYZ, he not only performed his given tasks successfully but also cleared our backlog (pending work). He performed his duties with honesty and full devotion.
We wish him all success in his professional life.
Best wishes, Clive