Canto 3 -
Araṇya-kāṇḍa
Chapter 2: Rāma Encounters the Rākṣasa Virādha
Text 3.2.20
इति ब्रुवति काकुत्स्थे बाष्पशोकपरिप्लुते।
अब्रवील्लक्ष्मणः क्रुद्धो रुद्धो नाग इव श्वसन्॥
iti bruvati kākutsthe bāṣpa-śoka-pariplute
abravīl lakṣmaṇaḥ kruddho ruddho nāga iva śvasan
iti = in this manner; bruvati = spoke; kākutsthe = when the descendant of Kakutstha; bāṣpa-śoka-pariplute = while being sorrowfully overwhelmed with tears in His eyes; abravīt = replied; lakṣmaṇaḥ = Lakṣmaṇa; kruddhaḥ = in anger; ruddhaḥ = arrested by mantras; nāgaḥ = a snake; iva = like; śvasan = while sighing.
When the descendant of Kakutstha spoke in this manner while being sorrowfully overwhelmed with tears in His eyes, Lakṣmaṇa replied while sighing in anger like a snake arrested by mantras.
It is implied that Lakṣmaṇa sighed [in anger] by seeing Rāma in distress.