SB 11.5.17

eta ātma-hano ’śāntā
 ajñāne jñāna-māninaḥ
sīdanty akṛta-kṛtyā vai
 kāla-dhvasta-manorathāḥ
Synonyms: 
ete — these; ātma-hanaḥ — killers of the self; aśāntāḥ — devoid of peace; ajñāne — in ignorance; jñāna-māninaḥ — presuming to have knowledge; sīdanti — they suffer; akṛta — failing to perform; kṛtyāḥ — their duty; vai — indeed; kāla — by time; dhvasta — destroyed; manaḥ-rathāḥ — their fanciful desires.
Translation: 
The killers of the soul are never peaceful, because they consider that human intelligence is ultimately meant for expanding material life. Thus neglecting their real, spiritual duties, they are always in distress. They are filled with great hopes and dreams, but unfortunately these are always destroyed by the inevitable march of time.
Purport: 

There is a similar verse in Śrī Īśopaniṣad (3):

asuryā nāma te lokā
 andhena tamasāvṛtāḥ
tāṁs te pretyābhigacchanti
 ye ke cātma-hano janāḥ

“The killer of the soul, whoever he may be, must enter into the planets known as the worlds of the faithless, full of darkness and ignorance.”