ייִדישער מחשבֿה אויף משלי 12:21

Seventh, when service is only derived from the Torah, a person can never be sure that he will not stumble. For in that kind of service, the force of evil passion is always lurking in ambush, waiting for the time when he will neglect it. But when the service is prompted by the understanding, a man can be sure that he will not stumble and sin, for the soul is attracted to service of G-d only after physical lust has been slayed (overcome) and the intellect has obtained the victory over it, and controls it according to his will and desire. Hence, this type of service affords a guarantee against stumbling, and one who has attained it, is guarded from sin, as Scripture says, "There shall no evil happen to the righteous" (Mishlei 12:21).

And if it was completed through one of them, let him thank the Creator who fulfilled his desire, and thank the person through whom it was done, for his good will towards him, and that the Creator brought his benefit through him, and it is known that the Creator does not bring good except through the tzadikim (righteous), and it is rare that He brings a loss through them, as the sages said "merit occurs through the meritorious and guilt through the guilty" (Bava Basra 119b), and the verse "No wrong shall be caused for the righteous" (Mishlei 12:21 - Rashi "No sin will chance before him inadvertently").

When you reach this level of abstinence from prohibited things without needing to force your nature and without resistance from yourself, you will belong to the class of those saved from sin and stumbling which the verse says of them: "no mischief shall befall the righteous" (Mishlei 12:21).