If you would spare Zheng as a host of the eastern roads, we are willing to provide hospitability and aid to your eastbound diplomatic missions. There could be no harm to you in this.
Uttered by Zhu Zhiwu (燭之武), a Zheng courtier, during his negotiation with the Count Mu of Qin (秦穆公) who was laying siege to the state of Zheng. Later used idomatically as a generic term for a host.