The Bhagavad Gita · Chapter 4 · verse 4.7
Whenever there is decline of dharma, O Bharata, and rise of adharma, then I manifest myself.
Sanskrit (Devanagari)
यदा यदा हि धर्मस्य ग्लानिर्भवति भारत। अभ्युत्थानमधर्मस्य तदात्मानं सृजाम्यहम्॥
Transliteration
yadā yadā hi dharmasya glānir bhavati bhārata; abhyutthānam adharmasya tadātmānaṁ sṛjāmy aham
English translation
Whenever there is decline of dharma, O Bharata, and rise of adharma, then I manifest myself.
Meaning — what the verse is actually saying
The famous avatāra verse. The divine descends into form whenever the moral order is in crisis. The verse is the theological warrant for the entire avatar tradition of Hinduism.
Modern practice — what to do today because of this
For the secular reader: the verse can be read as a description of how correction tends to arise in any system. When dysfunction peaks, something rises to address it. Recognise the moment in your own life when the corrective is appearing — and align with it rather than resist.