Where does the phrase "cultivate one's mind internally and one's behavior externally" come from?

Zuo's Discernment

Internal cultivation of the heart and external cultivation of the behavior, from Song? Ouyang Xiu's "Zuo's Discernment": "The gentleman's cultivation of the body is also to correct his heart internally and his appearance externally. It means that a gentleman should cultivate his inner character first, and pay attention to his outer appearance second. It objectively points out the importance of human cultivation and character.

Ouyang Xiu (August 1, 1007 - September 22, 1072), the word Yongshu, the number of drunkenness, the late number of the Sixth Jushi, Jizhou Yongfeng (today's Ji'an City, Jiangxi Province, Yongfeng County), Jingde four years (1007) was born in Mianzhou (today's Mianyang City, Sichuan Province), the Northern Song Dynasty politicians, writers.