"yada yada hi dharmasya
glanir bhavati bharata
abhyutthanam adharmasya
tadatmanam srjamy aham"
The Meaning Is:
"Sri Krishna said: Whenever and wherever there is a decline in virtue/religious practice,
O Arjuna, and a predominant rise of irreligion—at that time I descend Myself,
i.e. I manifest Myself as an embodied being."
O Arjuna, and a predominant rise of irreligion—at that time I descend Myself,
i.e. I manifest Myself as an embodied being."