This is also stated by Brahmā in Śrīmad-Bhāgavatam (SB 10.14.4):
- śreyaḥ-srutiṁ bhaktim udasya te vibho
- kliśyanti ye kevala-bodha-labdhaye
- teṣām asau kleśala eva śisyate
- nānyad yathā sthūla-tusāvaghātinām
"My dear Lord, devotional service unto You is the best path for self-realization. If someone gives up that path and engages in the cultivation of knowledge or in speculation, he will simply undergo a troublesome process and will not achieve his desired results. A person who beats an empty husk of wheat cannot get grain, and one who engages simply in speculative knowledge cannot achieve the desired result of self realization. The only gain is trouble."