Chapter 4 · verse 40 · gita.yoga.org

Bhagavad Gita 4.40

अज्ञश्चाश्रद्दधानश्च संशयात्मा विनश्यति। नायं लोकोऽस्ति न परो न सुखं संशयात्मनः

The ignorant, the faithless, and the doubting self go to destruction; there is neither this world nor the other, nor happiness for the doubting one.