Rashi and R. Bachye #1: With reference to the prohibition against making an image that he just mentioned, Moshe now adds ?which Hashem commanded us not to do?. .

Ramban (on Pasuk 20): Refer to 4:22:1:2*.

R. Bachye #2: With reference to the Keruvim, the Torah is now prohibiting their manufacture anywhere else other than in the Beis-Hamikdash, where Hashem commanded them to be placed. ^{1 2}