Srimad-Bhagavatam: Canto 10 - Chapter 1 - Verse 38
Sanskrit:
यथामयोऽङ्गे समुपेक्षितो नृभि-र्न शक्यते रूढपदश्चिकित्सितुम् ।यथेन्द्रियग्राम उपेक्षितस्तथारिपुर्महान् बद्धबलो न चाल्यते ॥ ३८ ॥
ITRANS:
yathāmayo ’ṅge samupekṣito nṛbhirna śakyate rūḍha-padaś cikitsitumyathendriya-grāma upekṣitas tathāripur mahān baddha-balo na cālyate
Translation:
As a disease, if initially neglected, becomes acute and impossible to cure, or as the senses, if not controlled at first, are impossible to control later, an enemy, if neglected in the beginning, later becomes insurmountable.