The Gita Series - A triune pilgrimage - 052 - Ch 04 - Slokas 7 to 8
yadā yadā hi dharmasya glānir bhavati bhārata
abhyutthānam adharmasya tadātmānaṁ sṛijāmyaham
Whenever there is a decline in righteousness and an increase in unrighteousness, O Arjun, I manifest Myself on earth.
paritrāṇāya sādhūnāṁ vināśhāya cha duṣhkṛitām
dharma-sansthāpanārthāya sambhavāmi yuge yuge
To protect the pious, to annihilate the wicked, and to reestablish dharma I appear on this earth, age after age.