Mutable karma. Since the strength of this karma, virtuous or not, is weak, it will likely not cause any effect when met with a counteracting condition. For negative karma to become mutable, we must bring forth this counteracting condition, i.e., repentance. According to the Mahayanabhidharma-sangiti-shastra, the way to turn all evil karma committed since beginningless time into mutable karma is to repent and vow never to commit again. To repent past wrongdoings and resolve never to repeat again are the two key elements to turn immutable into mutable karma.

- Quote from The Right View, "On Cause and Effect"