BG Chap 10 - The nature of Kṛṣṇa that generates and nourishes bhakti
Kṛṣṇa is the source of all spiritual and material worlds. Everything emanates from Him. He is the cause of the whole material manifestation headed by Brahmā and Śiva. The Mahā-Nārāyaṇa Upaniṣad says that prior to creation only Nārāyaṇa existed, not Brahmā nor Śiva nor Varuṇa, nor Agni, nor heaven and earth, nor the constellations, nor the sun. The whole world moves because of Him alone, in the form of Paramātmā. In the form of avatāras like Nārada, He alone causes sādhanas such as bhakti, jñāna, tapas and karma, and the goals of these sādhanas to operate. The Lord is the material and efficient cause of everything that exists besides Himself. Being convinced thru faith by this knowledge obtained from guru, the intelligent persons endowed with bhāva in the forms of dāsya, sakhya or other relationships worship Kṛṣṇa. Thus knowing of His greatness leads to full surrender and full surrender is followed by bhāva, love.