The word "teaching" can be translated as a verb. Alternate translation: "do not forget what I have taught you" (See: [[rc://en/ta/man/jit/figs-abstractnouns]])
This phrase says in positive terms what the previous phrase says in negative terms. Here the word "heart" represents the mind. The word "commandments" can be translated as a verb. Alternate translation: "always remember what I have commanded you" (See: [[rc://en/ta/man/jit/figs-parallelism]] and [[rc://en/ta/man/jit/figs-metonymy]] and [[rc://en/ta/man/jit/figs-abstractnouns]])