Valmiki Ramayana Yuddha Kanda Sarga 17 Shloka 44

प्रणिधाय: employing spies, सूक्ष्मबुद्धिना: who has subtle intellect, चारेण: by a spy, यथावत् in the same way, परीक्ष्यच after examining, ततः thereafter, यथान्यायम् in appropriate manner, परिग्रहः accept, कार्यः action.

"By employing a spy with subtle intellect to examine Vibheeshana, we can act in an appropriate manner to accept him (Vibheeshana)."