EXOD161 When one hears the admonition of the Sages and of others who offer reproof, he should listen, be receptive and compliant, and repent; he should be willing to accept the complete admonishment without detracting from what is said. Indeed, this person is able to emerge, in one brief moment, from darkness to great light. For from the moment that he listens and takes heed, and his heart understands and returns; when upon hearing his admonisher's words he accepts them, and he resolves from that day onwards to do as the Torah sages [Yirmeyahu 2:8] have instructed him--to be heedful when exhorted by those who astutely grasped the nature of the times [I Divrei Hayamim 12:33]--he will then be able to effectively repent, and he will be a completely changed individual. From the moment he has determined in his mind and taken on the inner commitment to follow through with this, he has acquired for himself the merits and rewards of all the mitzvos and moral injunctions [that he has yet to fulfill] [i.e., this commitment alone is regarded as if he has already fulfilled all of his obligations]. How fortunate is such a person, for in one brief moment, he has cleansed his soul! [Yirmeyahu 3:11]. Similarly, our Sages, z"l, said (Mechilta 12:28): "'The Children of Israel went and did...' [this verse][this is a reference to the Korban Pesach]--did they act upon it without delay? It wasn't until the fourteenth of the month that they did so! Yet, once they have resolved to do so, the Torah accredits them as having done so without delay."