Shaking the garments is Jacob’s act of taking off his garments and shaking them before his brethren. Jacob said, “I take off my garments, and I shake them before you” (2 Nephi 9:44).
Jacob prayed that the God of his salvation would view him with “his all-searching eye”. He said that at the last day the God of Israel would witness that he had “shook your iniquities from my soul” and was “rid of your blood” (2 Nephi 9:44).