Srimad-Bhagavatam: Canto 3 - Chapter 1 - Verse 28

Sanskrit:

कच्चिद्वरूथाधिपतिर्यदूनांप्रद्युम्न आस्ते सुखमङ्ग वीर: ।यं रुक्‍मिणी भगवतोऽभिलेभेआराध्य विप्रान् स्मरमादिसर्गे ॥ २८ ॥

ITRANS:

kaccid varūthādhipatir yadūnāṁpradyumna āste sukham aṅga vīraḥyaṁ rukmiṇī bhagavato ’bhilebheārādhya viprān smaram ādi-sarge

Translation:

O Uddhava, please tell me, How is Pradyumna, the commander in chief of the Yadus, who was Cupid in a former life? Rukmiṇī bore him as her son from Lord Kṛṣṇa, by the grace of brāhmaṇas whom she pleased.

Purport:

According to Śrīla Jīva Gosvāmī, Smara (Cupid, or Kāmadeva) is one of the eternal associates of Lord Kṛṣṇa. Jīva Gosvāmī has explained this very elaborately in his treatise Kṛṣṇa-sandarbha.