Canto 1 - Boyhood
Bāla-kāṇḍa
Chapter 46: Diti’s vow to kill Indra
Text 1.46.6

पूर्णे वर्षसहस्रे तु शुचिर्यदि भविष्यसि।
पुत्रं त्रैलोक्यभर्तारं मत्तस्त्वं जनयिष्यसि॥

pūrṇe varṣa-sahasre tu śucir yadi bhaviṣyasi
putraṁ
trailokya-bhartāraṁ mattas tvaṁ janayiṣyasi

pūrṇe varṣa-sahasre tu = for 1,000 years; śuciḥ yadi bhaviṣyasi = if you are pure; putram = to a son; trailokya-bhartāram = who will be the master of the three worlds; mattaḥ = by my mercy; tvam janayiṣyasi = then you will give birth.

If you are pure for 1,000 years, then, by my mercy, you will give birth to a son who will be the master of the three worlds.