dig heels in
dig one's heels in
Fig. to refuse to alter one's course of action or opinions; to be obstinate or determined. The student dug her heels in and refused to obey the instructions. I'm digging in my heels. I'm not going back.
dig your heels in
to refuse to do what other people are trying to persuade you to do, especially to refuse to change your opinions or plans We suggested it would be quicker to fly, but she dug her heels in and insisted on taking the train.