When I quit (due to stress, in a high work load phase of a project), he included my phrases verbatim in my written job reference (these are common in Germany). He literally wrote that I was unfocused and easily overworked. When I complained, he made sure to let me know that the stated issues were just what I told him in our 1:1 meetings. I can only assume malice, since they were really unhappy about me quitting and they expected the project deadline to be missed because of it.