Here we have an example of the historical present-tense saith that Joseph Smith missed in his editing for the 1837 edition. As explained under 1 Nephi 2:1, Joseph usually emended the historical present tense to the past tense. Interestingly, here in 3 Nephi 26:2 no subsequent edition has ever made the change. There is a nearby example, in 3 Nephi 27:2, where Joseph marked the change from saith to said in 𝓟 but it was never implemented in the 1837 edition. In that case, 20th-century editions of the Book of Mormon made the change to said. For a complete discussion of the historical present tense in the original Book of Mormon text, plus its normal editing to the past tense, see under historical present in volume 3.
Summary: Maintain the present-tense saith in 3 Nephi 26:2; such usage is common in the original Book of Mormon text, although most cases have been edited to said.