en_tn/pro/22/20.md

Have I not written for you

The answer to this question is "yes." AT: "I have written for you" (See: rc://en/ta/man/translate/figs-rquestion)

instruction and knowledge

These two words mean basically the same thing and emphasize the content of the thirty sayings. (See: rc://en/ta/man/translate/figs-doublet)

to those who sent you

This implies that the person listening is or will be a messenger, a function similar to a diplomat or a negociator.