《左传·僖公·僖公三十年》
九月初十日，晋文公、秦穆公包围郑国，因为郑国对晋国无礼，而且心向着楚国。
九月甲午，晋侯、秦伯围郑，以其无礼于晋，且贰于楚也。
On the 10th day of the ninth month, Duke Wen of Jin and Duke Mu of Qin besieged Zheng state because Zheng state was rude to Jin state and was in favor of Chu state.