Canto 3 -
Araṇya-kāṇḍa
Chapter 18: Śūrpaṇakhā Disfigured

Rāma smilingly explained why He could not marry Śūrpaṇakhā and asked her to accept Lakṣmaṇa as her husband. Lakṣmaṇa logically explained to Śūrpaṇakhā that she should marry Rāma. When she requested Rāma to marry her and tried to eat up Sītā, Lakṣmaṇa cut off her ears and nose on the order of Rāma. Śūrpaṇakhā then approached Khara.