there is no problem in putting a picture on the article but do you have a picture which clearly represents muhammad in accordance to the textual descriptions of his physical appearance as well as his life and if there is such picture available then is that picture credible and cited in any scholastic works notably if above two conditions are met and the picture not titled as muhammad but by the artists reference if above three conditions are true then i am right here to support the picture otherwise please find out such picture and come back