(in) honor bound (to do something)
Having an obligation (to do something) because it is morally correct or required by one's sense of duty or integrity. It pains me to turn you in to the police, my friend, but I am honor bound—I wouldn't be able to live with myself if I ignored a crime. I knew it would cost me my job, but I felt in honor bound to tell them that the data breach was my fault.
honor bound
Obliged by one's personal integrity, as in She was honor bound to admit that it was her work and not her sister's. Also see on one's honor.
(in) honour bound
obliged by your sense of honour. honor bound
Under an obligation enforced by the personal integrity of the one obliged: I was honor bound to admit that she had done the work.