For these three verses, Limhi is quoting the Lord, perhaps according to the words of Abinadi. Note, for instance, the similar language in Abinadi’s warning to the people of king Noah:
Here in Mosiah 7:29–31, Limhi uses the pronoun he for the second and third cases, but the use of again as well as the repetition of my people shows that the pronoun he refers to the Lord (not Abinadi or even Limhi). In the first case, Limhi uses the present perfect (hath said), which implies that the Lord said this sometime in the past (perhaps through Abinadi, although not necessarily so). In the second and third cases, the original text has the present-tense use of saith. One could interpret these two cases of saith as instances of the historical present, which is apparently how Joseph Smith interpreted them when he decided to edit them to said for the 1837 edition. In other words, his editing in 𝓟 implies that each of the three quotations specifically refers to something the Lord had stated at some precise time in the past. However, this editing of Joseph’s was not implemented in the 1837 edition, probably because it was decided to interpret the two presenttense forms of saith as referring to eternally true statements from the Lord.
The critical text will here follow the earliest textual reading and does not need to decide between the two possible interpretations. Instead, for both instances here in Mosiah 7:30–31, the original present-tense form saith will be maintained. This problem in interpreting present-tense forms is a persistent one in the text. For two similar examples where the present-tense form can be interpreted either as the historical present or as the eternal present, see under 2 Nephi 31:10–11; for more examples, plus a general discussion, see historical present in volume 3.
Summary: Maintain both cases of the present-tense saith in Mosiah 7:30–31.