Bhagavatapurana 6.1.12

6.1.12

nāśnataḥ pathyamevānnaṃ vyādhayo 'bhibhavanti hi /
evaṃ niyamakṛdrājan śanaiḥ kṣemāya kalpate //

12. Diseases do not indeed invade those who eat only the wholesome food; similarly, O King, he who practises self-discipline is gradually able to attain (knowledge of Truth *i.e.*, the fearless state).