Srimad-Bhagavatam: Canto 11 - Chapter 1 - Verse 19
Sanskrit:
एधमाने गुणे सत्त्वे देवानां बलमेधते ।असुराणां च रजसि तमस्युद्धव रक्षसाम् ॥ १९ ॥
ITRANS:
edhamāne guṇe sattvedevānāṁ balam edhateasurāṇāṁ ca rajasitamasy uddhava rakṣasām
Translation:
With the increase of the mode of goodness, the strength of the demigods similarly increases. When passion increases, the demoniac become strong. And with the rise of ignorance, O Uddhava, the strength of the most wicked increases.