Valmiki Ramayana Yuddha Kanda Sarga 87 Shloka 18

भ्रातृपुत्रेण brother's son, इति thus, उक्तःhaving spoken, विभीषणः Vibheeshana, प्रत्युवाच replied back, राक्षस Rakshasa, मछचीलम् my disposition, अजानन्निव as though you did not know, किम् why, विकत्थसे speak like this

Indrajith having spoken like that, Vibheeshana replied," why do you speak like that as though you do not know my disposition?"