Śrī Caitanya Caritamrta · Text Madhya 24.140
শ্রেয়ঃসৃতিং ভক্তিমুদস্য তে বিভো
ক্লিশ্যন্তি যে কেবল-বোধলব্ধয়ে ।
তেষামসৌ ক্লেশল এব শিষ্যতে
নান্যদ্যথা স্থূলতুষাবঘাতিনাম্ ॥ ১৪০ ॥
śreyaḥ-sṛtiṁ bhaktim udasya te vibho
kliśyanti ye kevala-bodha-labdhaye
teṣām asau kleśala eva śiṣyate
nānyad yathā sthūla-tuṣāvaghātinām
Translation
“ ‘My dear Lord, devotional service unto You is the only auspicious path. If one gives it up simply for speculative knowledge or the understanding that these living beings are spirit souls and the material world is false, he undergoes a great deal of trouble. He only gains troublesome and inauspicious activities. His actions are like beating a husk that is already devoid of rice. His labor becomes fruitless.’
Read Śrīla Prabhupāda's purport on Vedabase.io