《史记·三十世家·郑世家》
二十七年，郑君才朝拜周桓王，桓王对郑攫取庄稼一事很生气，没有按礼仪对待他。
二十七年，始朝周桓王。桓王怒其取禾，弗礼也。
In the twenty-seventh year, the ruler of Zheng came to court to Duke Huan of Zhou, but Duke Huan was angry about Zheng's seizure of crops and did not treat him with the proper respect.