In Parshat Eikev there are many topics that Moshe addresses. One major idea mentioned throughout Perakim ט and י is that of the sins of Bnai Yisrael. In Perek ט the main sin that is always referred back to is חטא העגל. The Perek starts out with חטא העגל then mentions the sins in תבערה ,מסה, and קברות התאווה. Then Moshe briefly mentions the major sin of מרגלים. However, Moshe goes back again to חטא העגל, mentioning his prayer to Hashem that saved Bnai Yisrael. In Perek י there is a repetition of the story of חטא העגל with other small stories including the ארון and Shevet לוי mixed in between. The obvious question is, why does Perek י repeat the previous Perek, when חטא העגל was mentioned several times already? My Chumash teacher, Rabbi Zvi Engle, gives a great answer to this. He says that if you line up Perakim ט and י side by side, is seen that Perek י is an atonement for the sins mentioned in Perek ט. For example, in Perek ט it talks about Bnai Yisrael’s sin with the image of .חטא העגלThen in Perek י it mentions the making of the ארון so that when Moshe goes up on to הר סיני Bnai Yisrael will have something to look at as a reminder that Moshe is getting the Torah, and then they will not forget Hashem again. Another example is when in Perek ט Moshe prays for Aharon after his involvement with the sin. Then in Perek י we see a result of this where Aharon dies and the Leviim are appointed to teach Bnai Yisrael. We see how each Perek compliments the other, and for every action of Bnai Yisrael, there is a reaction to prevent them from doing something bad again.