Visualize Jacob as he took off his high priestly robes and shook them saying, "I shake them before you" (9:44). Why would he do that? He wants his people to be responsible. He is telling them that he has shaken their iniquities from his soul as if saying, "I’m not bearing your iniquities any longer." Jacob couldn’t have that impurity on him as the high priest, otherwise that would compromise his ability to be a pure officiator in the temple.
This scene must have been very dramatic. Imagine if President Nelson during General Conference took off his coat and stood there and shook it in front of everybody and said, "I have given you all that I can. Now I shake off any responsibility for you and your sins." How would you feel? Wouldn’t that leave an impression? That is how ancient prophets often got their points across. In this case, Jacob wanted to absolutely impress upon his people the importance of holiness. God wants his people to be holy. Several key words are used by Jacob in this chapter, including "judgment" (7 times), "remember" (8 times), and "deliver" (12 times). But the dominant key word in this temple-covenant speech is "holy." It appears 23 times, and "holiness" two times more. The dominant name used by Jacob here for the Lord is "the Holy One of Israel," which appears thirteen times. One may well conclude that the main theme of Jacob’s temple speech here is holiness, Holiness to the Lord.
Parry, Donald W., "Symbolic Action as Prophecy in the Old Testament" in Sperry Symposium Classics: The Old Testament, ed. Paul Y. Hoskisson (Provo and Salt Lake City, UT: Religious Studies Center, Brigham Young University and Deseret Book 2005), 337–355.