The phrase, “when ye shall come unto me,” refers to the brother of Jared’s death, not his present interview with the future Messiah. The commandment to “write [these things] and… seal them up” to prevent their being interpreted was not a physical sealing, since Mosiah interpreted them. Rather, they were a mental “sealing,” since the brother of Jared wrote “in a language that… cannot be read.” Moroni had made the same statement about his own writings (Morm. 9:34). They were sealed because they could not be read by typical human means. (See commentary accompanying Ether 5:1.)