Dear …
All companies go through lean times where they have to tighten up on spending and get a firm grip on their expenses in order to take them through to more bountiful times. As it is, __ (name of firm) __ is going through such a time now where we are having to make sacrifices in many areas.
I know that employees expect periodic raises and, when their company is going through financially successful times, they should be able to share in the rewards. However, during those lean periods, everyone must share in the sacrifices.
I thank you for your understanding of our circumstances and your willingness to hold off on a raise until such time that our company is in a better financial position. Your loyalty to our company is greatly appreciated and will not be forgotten.
Sincerely,