For to those who thus examine themselves and conform their hearts to the Lord, nothing adverse shall happen; for indeed, their hearts are strengthened by confidence in the Lord, as it is written, “They who trust in the Lord are as Mount Zion; he who dwells in Jerusalem shall not be moved forever.” For if at any time, the crafty one shall be presumptuously bold against them, chiefly that he may break the rank of the saints and cause a division among brethren; even in this the Lord is with them, not only as an avenger on their behalf but also when they have already been beaten, as a deliverer for them.
Source: Letter 11.6