The word "eikev" that is used to title the third portion of Sefer Devarim is usually translated as "if" - based on the first verse which reads: "and it will be 'if' you will listen to my laws." But Rashi has a homiletic interpretation which is based on the idea that "e-k-v" is also the root of the Hebrew word for heel. Rabbi Dunner uses his grandfather's Mikdash Halevi to expand on this idea, which adds context from multiple sources, and even suggests another interpretation for the word "eikev."