Nisan-Perfecting Our Speech-9
The Berditchever taught that a person who has an opportunity to gain profit by lying, but holds fast to the truth because he remembers the prohibition against falsehood, is rewarded not only for adhering to the prohibition, but also for retaining it in his mind.
Thus, he who abstains from a sin or performs a good deed receives also the reward for studying the portion of the Torah concerning it.
He whose mouth and heart are not in perfect harmony cannot expect his prayers to be acceptable on high. Satan will claim that though he prays with his mouth, he does not believe in God’s powers in his heart. (Emet Kaneh, page 56)