Chp. 31 verses 22 -30: Finishes off the prophecy of the future sins. So Moshe wrote the song of Ha'azinu on that day and taught it to the people. He commanded Yehoshua to be strong and that Hashem would be with him. He finished writing the words of the Torah. He then commanded the Levites to place the Torah next to the Ark so that it could be a witness against them, because he knew that they would rebel against Hashem. Then Moshe was told to assemble the people to teach them the passages of Ha'azinu, which would again remind them of the consequences of turning against Hashem.