CC Ādi 5.151

niṣedha karite nāre, yāte choṭa bhāi
mauna dhari’ rahe lakṣmaṇa mane duḥkha pāi’
Word for word: 
niṣedha karite nāre — unable to prohibit Lord Rāmacandra; yāte — because; choṭa bhāi — younger brother; mauna dhari’ — becoming silent; rahe — remains; lakṣmaṇa — Lakṣmaṇa; mane — in the mind; duḥkha — unhappiness; pāi’ — getting.
Translation: 
As a younger brother He could not stop Lord Rāma from His resolution, and so He remained silent, although unhappy in His mind.