Here the 1849 LDS edition reads hath instead of the expected have. This change was undoubtedly a typo. Perhaps the 1849 typesetter was influenced by the preceding singular noun phrase “so great faith”, which led him to expect the third person singular hath rather than have. Of course, the subject in this sentence is I, not “so great faith” (which acts as a fronted direct object in this sentence). The 1852 LDS edition restored the have, the correct verb form for the subject I. It is true that in the original text there is some evidence for expressions equivalent to “I hath” (see the discussion under 2 Nephi 8:16), but here in 3 Nephi 19:35 this later instance of “I hath” is clearly secondary. Here is one more instance of “I hath” in the original text, although in this case the hath occurs in a conjoined predicate:
Summary: Maintain in 3 Nephi 19:35 the original have, the earliest reading as well as what we expect with the subject pronoun I.