Bhagavad Gita 8.14

To him who constantly thinks of Me and nothing else, to such an ever-faithful devotee, O Arjuna, I am ever accessible.

अनन्यचेताः सततं यो मां स्मरति नित्यशः।
तस्याहं सुलभः पार्थ नित्ययुक्तस्य योगिनः॥

ananyacetāḥ satataṃ yo māṃ smarati nityaśaḥ|
tasyāhaṃ sulabhaḥ pārtha nityayuktasya yoginaḥ||

English translation (above): Shri Purohit Swami (1935), public domain. Sanskrit text via github.com/gita/gita (Unlicense).