Shloka 5.52.2
दूतधर्म-परामर्शः (Envoy-Immunity and Royal Counsel in Ravana’s Court)
वधे तस्य समाज्ञप्ते रावणेन दुरात्मना।निवेदितवतो दौत्यं नानुमेने विभीषणः।।।।
vadhe tasya samājñapte rāvaṇena durātmanā | niveditavato dautyaṁ nānumene vibhīṣaṇaḥ ||
When the wicked-souled Rāvaṇa ordered his killing, Vibhīṣaṇa did not approve, for he had already declared himself an envoy.
Vibhishana did not approve of the killing of Hanuman, who had declared that he was an envoy (of Sri Rama) when the wicked Ravana ordered his murder.
The dharma of diplomacy: once a person has openly declared envoy-status, killing him violates established righteous conduct and undermines truthful communication (satya) between opponents.
Rāvaṇa, enraged, commands Hanumān’s execution; the narration notes Vibhīṣaṇa’s immediate dissent based on dharmic norms.
Vibhīṣaṇa’s adherence to dharma over loyalty to wrongdoing—he refuses to endorse an unjust order.