In Parasha Netzavim, Devarim 30:16, we learn the commandment to love Hashem, to walk in His ways, and to keep "His commandments [mitzvosav] and His statutes [v'chukosav] and His ordinances [v'mishpatav]."  I thought this verse might be distinguishing between the written Torah, oral Torah, and rabbinic law, or perhaps between Torah, rabbinic law, and customs.  But I can't find a source that explains this.  To what is the verse referring?