Idiom/Phrase/Proverb to describe a scenario where a person who saved me from a bad habit has now fallen into the the same habit

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 I am looking for a proverb, idiom, phrase, or a historical reference which I could use to subtly remind that person of that fact.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.

Solution 1:

2 sentences that comes to my mind are:

Physician, heal yourself! 1

and

The shoemaker's children go barefoot 2

Both are referring to people who are able to help others, but have problems help themselves. Although the situation is a bit other, because in your case the person that have helped you got the same problem not in the same time, but afterwards.

Disclaimer while in first case I'm sure it has the same meaning as in my languange, in second case in Polish the saying is referring to the shoemaker going barefoot himself.