Bhagavad Gita 4.40
But the ignorant man, and he who has no faith, and the skeptic are lost. Neither in this world nor elsewhere is there any happiness in store for him who always doubts.
अज्ञश्चाश्रद्दधानश्च संशयात्मा विनश्यति।
नायं लोकोऽस्ति न परो न सुखं संशयात्मनः॥ajñaścāśraddadhānaśca saṃśayātmā vinaśyati|
nāyaṃ loko'sti na paro na sukhaṃ saṃśayātmanaḥ||
English translation (above): Shri Purohit Swami (1935), public domain. Sanskrit text via github.com/gita/gita (Unlicense).