According to John Welch, Benjamin knew and also referred to several concepts that were found on the small plates or were traditional in Nephite culture. One example is found in Mosiah 2 in which Benjamin says :
"I said unto you that I had served you, walking with a clear conscience before God, even so I at this time have caused that ye should assemble yourselves together . . . that I might rid my garments of your blood, at this period of time when I am about to go down to my grave, that I might go down in peace. (Mosiah 2:27-28).
Jacob expresses the same idea in 2 Nephi 9:44 ("I . . . am rid of your blood"), in Jacob 1:19 , and in Jacob 2:2 ("I . . . magnify mine office with soberness and that I might rid my garments of your sins"). [John W. Welch, "Benjamin, the Man: His Place in Nephite History," in King Benjamin's Speech: "That Ye May Learn Wisdom," p. 34]