It is hard to reason with him when he is angry.
reason with
idiomTo convince (someone) to do (or not do) something using rational arguments; to get (someone) to view something rationally.
She tried to reason with her brother, explaining that spending all his savings on a car was a bad idea.
Despite her best efforts to reason with the board members, they remained committed to the original, flawed strategy regardless of the mounting evidence against it.