Canto 2 -
Ayodhyā-kāṇḍa
Chapter 9: Kaikeyī Convinced by Mantharā
Text 2.9.21

चतुर्दश हि वर्षाणि रामे प्रव्राजिते वनम्।
प्रजाभावगतस्नेहः स्थिरः पुत्रो भविष्यति॥

caturdaśa hi varṣāṇi rāme pravrājite vanam
prajā-bhāva-gata-snehaḥ sthiraḥ putro bhaviṣyati

caturdaśa hi = for fourteen; varṣāṇi = years; rāme = Rāma; pravrājite = when is exiled; vanam = to the forest; prajā-bhāva-gata-snehaḥ = attain the favor and affection of the citizens; sthiraḥ = and become unshakable from His position; putraḥ = your son; bhaviṣyati = will.

When Rāma is exiled to the forest for fourteen years, your son will attain the favor and affection of the citizens and become unshakable from His position.