Srimad-Bhagavatam: Canto 10 - Chapter 1 - Verse 23
Sanskrit:
त्वयोदितोऽयं जगतो हिताययदा यदा वेदपथ: पुराण: ।बाध्येत पाषण्डपथैरसद्भि-स्तदा भवान् सत्त्वगुणं बिभर्ति ॥ २३ ॥
ITRANS:
tvayodito ’yaṁ jagato hitāyayadā yadā veda-pathaḥ purāṇaḥbādhyeta pāṣaṇḍa-pathair asadbhistadā bhavān sattva-guṇaṁ bibharti
Translation:
You originally enunciated the ancient religious path of the Vedas for the benefit of the whole universe. Whenever that path becomes obstructed by wicked persons following the path of atheism, You assume one of Your incarnations, which are all in the transcendental mode of goodness.