Bhagavad Gita · 12.5

क्लेशोऽधिकतरस्तेषामव्यक्तासक्तचेतसाम्।अव्यक्ता हि गतिर्दुःखं देहवद्भिरवाप्यते॥

kleśho 'dhikataras teṣhām avyaktāsakta-chetasām avyaktā hi gatir duḥkhaṁ dehavadbhir avāpyate

For those whose minds are attached to the unmanifest, the path is much more difficult. The goal of the unmanifest is very hard for embodied beings to attain.

— Bhagavad Gita 12.5

Source: Sacred-Texts.com (Sanskrit) + Bhagavad-Gita.io (translations)