Srimad-Bhagavatam: Canto 10 - Chapter 1 - Verse 3

Sanskrit:

तं शम्बर: कामरूपी हृत्वा तोकमनिर्दशम् ।स विदित्वात्मन: शत्रुं प्रास्योदन्वत्यगाद् गृहम् ॥ ३ ॥

ITRANS:

taṁ śambaraḥ kāma-rūpīhṛtvā tokam anirdaśamsa viditvātmanaḥ śatruṁprāsyodanvaty agād gṛham

Translation:

The demon Śambara, who could assume any form he desired, kidnapped the infant before He was even ten days old. Understanding Pradyumna to be his enemy, Śambara threw Him into the sea and then returned home.

Purport:

Śrīla Viśvanātha Cakravartī points out that according to the Viṣṇu Purāṇa, Pradyumna was kidnapped on the sixth day after His birth.