It is very simple to tell employees things that do not help them. Recognizing when to remain silent or when use different formulations is more difficult. Thus, what should managers not say? Toolbox.com pointed at some specific errors.
"I believe that you will soon discover what to do."
Workplaces are full of employees who have never heard what exactly constitutes a good performance in their jobs. Try not to make it your case. Employees need to know your expectations.
"I hope you do not mind, but ..."
Do not apologize for doing your job when managing the performance of your people. You do not have to ask anyone for permision to give feedback.
"Well done, keep up."
Vague praise is misleading and most importantly demotivating. Both the positive and negative feedback reguire the same thing - to be meaningful, it must be factual.
"Give me your feedback now."
If you suddenly point at someone with a requirement to give you his feedback, you will not learn anything beneficial. If you want to learn how your people perceive your management style, rather ask what you can do differently for them to be more satisfied.
-kk-