BG Chap 11 - Kṛṣṇa's glorification of unalloyed bhakti

Only by ananya bhakti, it is possible to understand Kṛṣṇa as He is, see Him, enter into the mysteries of His understanding or become connected to Him. Even if one desires nirvāṇa mokṣa, then one can merge with Brahman only by ananya bhakti. This is the meaning of praveṣṭuṁ given by Viśvanātha Cakravarti. The guṇī-bhūtā-bhakti of the jñānīs remains as a small amount of ananya bhakti after the renunciation of jñāna at the time of death. By that they attain sāyujya mukti. Baladeva Vidyabhusana interprets praveṣṭuṁ to be connected with the Lord, and says that when one enters a city, one becomes intimately connected with the city and does not become the city or disappear completely in the city.
By study of the Vedas, by charity, by penance or by worship, it is possible to know the Lord only if one also has exclusive devotion to Him. Study of the Vedas means studying the Gopāla Tāpanī Upaniṣad, which describes Kṛṣṇa directly. Austerity means fasting on Kṛṣṇa’s appearance day and Ekādaśī as well as other days. Charity means giving one’s own possessions as gifts to the devotees. Worship means to worship Kṛṣṇa’s deity forms. Thus ananya bhakti is essential in all these instances. The word ‘tu’ in bhaktyā tv ananyayā (verse 11.54) indicates that the human form of Kṛṣṇa is very difficult to see and no other process except ananya bhakti can result in seeing that form.