All stretches are to be taken to a point where a gentle stretch is felt without causing pain, if a stretch is causing pain lessen the intensity of the stretch. If the stretch is still causing pain refrain from doing this stretch and contact your health professional for further advice.
There is no need to push these stretches, overstretching is counterproductive.
Continuous gentle stretching will allow you to gain increased flexibility quicker than if you over stretch and cause yourself an injury.
Stretch smart, not hard.