As discussed under 2 Nephi 4:15, the original text had a number of cases where the verb for the subject pronoun I ended in -(e)th, especially when there was some intervening text (such as “the Lord God” here in Jacob 2:28). The 1920 LDS edition removed the -(e)th ending here, but the critical text will restore it. For further discussion of the phrase “I saith”, see under 1 Nephi 11:3.