Original Text:
子曰由诲汝知之乎知之为知之不知为不知是知也
Translation:

The Master said, “Zilu, remark well what I am about to teach you! This is wisdom: to recognize what you know as what you know, and recognize what you do not know as what you do not know.”
Confucius, & Slingerland, E. (2003). Analects: With selections from traditional commentaries. Hackett Publishing.
The Master said, You (Zilu), shall I teach you what it means to know something? When you know, to know you know. When you don’t know, to know you don’t know. That’s what knowing is.
Confucius, & Watson, B. (2007). The Analects of Confucius. Columbia University Press.