Chapter 4 · Knowledge and Renunciation of Action · Krishna said
Bhagavad Gita 4.6 — How God takes birth
अजोऽपि सन्नव्ययात्मा भूतानामीश्वरोऽपि सन्। प्रकृतिं स्वामधिष्ठाय सम्भवाम्यात्ममायया ॥
ajo'pi sannavyayātmā bhūtānāmīśvaro'pi san | prakṛtiṃ svāmadhiṣṭhāya sambhavāmyātmamāyayā ||
Meaning
Though I am unborn and unchanging, and the Lord of all beings, I take birth through my own divine power, governing my own nature.