In this passage the 1837 edition accidentally set thou has instead of thou hast. What is interesting here is that this typo continued in the next three editions, showing the difficulty that editors and typesetters have sometimes had in recognizing a violation of the archaic biblical style. The critical text will, of course, maintain the original thou hast here in Mosiah 17:8. For further discussion, see under infl al endings in volume 3.
Summary: Maintain in Mosiah 17:8 the biblically styled thou hast, the earliest reading.