SB 3.1.28
kaccid varuthadhipatir yadunam
pradyumna aste sukham anga virah
yam rukmini bhagavato ’bhilebhe
aradhya vipran smaram adi-sarge
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
O Uddhava, please tell me, How is Pradyumna, the commander in chief of the Yadus, who was Cupid in a former life? Rukmini bore him as her son from Lord Krsna, by the grace of brahmanas whom she pleased.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
According to Srila Jiva Gosvami, Smara (Cupid, or Kamadeva) is one of the eternal associates of Lord Krsna. Jiva Gosvami has explained this very elaborately in his treatise Krsna-sandarbha.