Set a bad example is an expression you may use.

set an example:

set a good or bad example . Behave in a way that should (or will) be imitated, as in

 

• Dad was always telling Bill to set a good example for his younger brother, or They were afraid of setting a bad example for the other nations/. [Late 1700s]

(AHD)

Set a bad example is an expression you may use.

set an example:

set a good or bad example . Behave in a way that should (or will) be imitated, as in

• Dad was always telling Bill to set a good example for his younger brother, or They were afraid of setting a bad example for the other nations/. [Late 1700s]

(AHD)

Set a bad example is an expression you may use.

To do something or act in a way other will or should emulate; to act as a model for others, good or ill.

• John, please don't curse like that when you're angry—it sets a bad example for the kids. I try to set an example for my employees by always arriving to work on time, replying to emails and phone calls promptly, and taking care of problems as they arise.

(The Free Dictionary)

Set a bad example is an expression you may use.

set an example:

set a good or bad example . Behave in a way that should (or will) be imitated, as in

• Dad was always telling Bill to set a good example for his younger brother, or They were afraid of setting a bad example for the other nations/. [Late 1700s]

(AHD)