CC Madhya 25.153
ihā haite pābe sūtra-śrutira artha-sāra
Śrī Caitanya Mahāprabhu advised Prakāśānanda Sarasvatī, “Study Śrīmad-Bhāgavatam very scrutinizingly. Then you will understand the actual meaning of the Brahma-sūtra.”
Śrīla Bhaktisiddhānta Sarasvatī Ṭhākura states that without studying Śrīmad-Bhāgavatam one cannot understand the purport of the Brahma-sūtra (Vedānta-sūtra) or the Upaniṣads. If one tries to understand Vedānta philosophy and the Upaniṣads without studying Śrīmad-Bhāgavatam, one will be bewildered and, construing a different meaning, will gradually become an atheist or an impersonalist.