touch a sore spot

touch a sore spot

 and touch a sore point
Fig. to refer to a sensitive matter that will upset someone. (Fig. on the notion of touching an injury and causing pain.) I seem to have touched a sore spot. I'm sorry. I didn't mean to upset you. When you talk to him, avoid talking about money. It's best not to touch a sore point if possible.
See also: sore, spot, touch