My dear King, if a diseased person eats the pure, uncontaminated food prescribed by a physician, he is gradually cured, and the infection of disease can no longer touch him. Similarly, if one follows the regulative principles of knowledge, he gradually progresses toward liberation from material contamination.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
नाश्नतः पथ्यमेवान्नं व्याधयोऽभिभवन्ति हि । एवं नियमकृद्राजन् शनैः क्षेमाय कल्पते
nāśnataḥ pathyamevānnaṃ vyādhayo'bhibhavanti hi | evaṃ niyamakṛdrājan śanaiḥ kṣemāya kalpate
SB 6.1.12