Srimad-Bhagavatam: Canto 11 - Chapter 1 - Verse 42
Sanskrit:
द्विज उवाचनायं जनो मे सुखदु:खहेतु-र्न देवतात्मा ग्रहकर्मकाला: ।मन: परं कारणमामनन्तिसंसारचक्रं परिवर्तयेद् यत् ॥ ४२ ॥
ITRANS:
dvija uvācanāyaṁ jano me sukha-duḥkha-heturna devatātmā graha-karma-kālāḥmanaḥ paraṁ kāraṇam āmanantisaṁsāra-cakraṁ parivartayed yat
Translation:
The brāhmaṇa said: These people are not the cause of my happiness and distress. Neither are the demigods, my own body, the planets, my past work, or time. Rather, it is the mind alone that causes happiness and distress and perpetuates the rotation of material life.