Zhongjing 忠經 "Book of loyalty" is a Confucian treatise attributed to Ma Rong 馬融 (79-166) from the Later Han period 後漢 (25-220 CE). Ma Rong was an important Confucian scholar who had written a lot of commentaries on the Confucian Classics， but also on the Daoist books Laozi 老子 and Huainanzi 淮南子. Ma had quite a few disciples, among which a handful of brilliant scholars are to be found, like Zheng Xuan 鄭玄 or Lu Zhi 盧植. It was also Zheng Xuan who wrote a commentary on the Zhongjing.
The large corpus of the original writings of Ma Rong is lost, but Ma Guohan 馬國翰 (1794-1857), compiler of a series of reconstructions of lost texts, the Yuhan shanfang jiyi shu 玉函山房輯佚書), and Huang Shi 黄奭 (1809-1853), compiler of the series Hanxuetang congshu 漢學堂叢書, collected the surviving fragments of Ma's oeuvre. There is also an edition of Ma's collected writings called Ma Jizhang ji 馬季長集 from the Ming period 明 (1368-1644).
The Zhongjing is divided into 10 chapters and enriched with a commentary. It seems to be that the main text and the commentary were written by the same person, for which reasons later scholars doubted the authenticity of Ma Rong's authorship. The book is not mentioned in the oldest bibliographies, but is first mentioned in the bibliography Chongwen zongmu 崇文總目 from the Song period 宋 (960-1279). It is therefore quite probable that the Zhongjing was a Song-period book claiming the authorship of Ma Rong and Zheng Xuan.
There was a book with the same title written by a certain Hai Peng 海鵬. This fact was mentioned in the chronicle Liangchao zhi 兩朝志 (today lost?), which is itself quoted in the Yuan-period 元 (1279-1368) encyclopaedia Yuhai 玉海.
Ma Rong's Zhongjing is included in the series Jindai mishu 津逮秘書, Xuejin taoyuan 學津討源, Ershierzi quanshu 廿二子全書 and Congshu jicheng 叢書集成.