The first time I've heard this advice is from the book of “Happiness In A Nutshell” by Andrew Mathews says about;
The moment you get too attached to things, people, money ... you screw it up!
This book "Don’t Worry Make, Make Money" tells about what happens when you attach yourself to nothing. It shows that non attachment gives freedom and a win-win situation whatever the outcome of your doing.
My personal experience on making myself nonattached is like offering or giving free services. Whatever the outcome of my services will never be a failure because I did give all my best but when I satisfied my customer that’s the real good story.
What about if commitment is concerns? It does not mean that non-attachment is not making a commitment. Doing this kind of tricks has the same goals with commitment and that is to make things delivered. It’s the way how you do it and make it.