Standing or sitting, preferably in front of a mirror, place the hands with the palms facing each other, in the regular “prayer” posture, and press the palms against each other. At the same time, lower the hands little by little towards the abdomen, without letting them pull apart.
An easy exercise that can be performed at any point during the day, like the rest periods in the middle of any long-lasting manual labor, perhaps. However, it is important to introduce variety into your training program. This one exercise is not a substitute for the other specific exercises for stretching the fingers because it does not stretch all of them equally with the middle fingers being stretched more.