Bhagwad Gita
Chapter 4, Verse 7
यदा यदा हि धर्मस्य ग्लानिर्भवति भारत।
अभ्युत्थानमधर्मस्य तदाऽऽत्मानं सृजाम्यहम्।।4.7।।
Whenever and wherever there is a decline in religious practice, O descendant of Bharata, and a predominant rise of irreligion—at that time I descend Myself.