CC Madhya 25.100

ataeva brahma-sūtrera bhāṣya — śrī-bhāgavata
bhāgavata-śloka, upaniṣat kahe ‘eka’ mata
Word for word: 
ataeva — therefore; brahma-sūtrera bhāṣya — the commentary on the Brahma-sūtra aphorisms; śrī-bhāgavata — Śrīmad-Bhāgavatam; bhāgavata-śloka — the verses in Śrīmad-Bhāgavatam; upaniṣat — the explanations in the Upaniṣads; kahe — state; eka mata — the same version.
Translation: 
“Therefore it is to be concluded that the Brahma-sūtra is explained vividly in Śrīmad-Bhāgavatam. Also, what is explained in the verses of Śrīmad-Bhāgavatam has the same purport as what is explained in the Upaniṣads.