I am facing a dilemma. Someone I know once (long time back) helped me get into a good habit, and abandon the accompanying bad habit, and now they have fallen into the same trap as me. I want to let them know of this, but I can't find the proper way to do this. I am looking for a proverb, idiom, phrase, or a historical reference which I could use to subtly remind that person of that fact.
Being direct might get me a quicker response, but I am afraid beginning from that might make the person less receptive to my advice. I am looking for something that I can use to get the other person thinking before I finally approach this topic.
Something suggestive, yet powerful.
Any help would be greatly appreciated.