Working for a person that teaches banking

I have been working for a person who teaches investment banking. I have never received any tasks related to interest till now as I am a freelancer. I work as system administrator of the courses he teaches and now I have came accross "interest" word. I am needed to add the images containing this word into the system he use for teaching and that's all, nothing else id required of me. What should I do? I am trying to find a job where there is no doubt and will leave this one as there is a doubt. Should I keep the income or discard it?