The expression is "Give a man a fish, and you will feed him for a day. Teach a man to fish, and you will feed him for a lifetime."

For the person on the other side, if they are familiar with the idiom, they will fill-in the rest of it, and realize that they are being taught a useful skill that will help them in their life.

Being allergic to fish myself, but one who loves fishing, this one never really worked for me, but it works for most people.