As discussed under Alma 8:15, the second person singular ending for past-tense verb forms in Early Modern English was -(e)st, especially -st when the verb ended in the regular past-tense -ed. The Book of Mormon text, however, has a number of examples where the -(e)st ending is lacking (for a list, see under 2 Nephi 24:12). Thus the critical text will accept the use of thou had here in Alma 11:25 rather than the thou hadst that the 1911 LDS edition introduced into the LDS text. The RLDS text has continued with the original thou had.
We also see here in Alma 11:25 that the earliest extant text (the printer’s manuscript) read thou saidest, which John Gilbert, the 1830 typesetter, emended to thou saidst (he used a pencil to cross out the e in 𝓟). Either ending, -est or -st, was possible in Early Modern English. Although the current King James Bible has examples of only saidst (22 of them), in the original 1611 printing five of these were set as saidest, as in John 4:18 (given here in its 1611 accidentals): “In that saidest thou truely.” One, in Job 35:2, was set as saydest in the 1611 King James Bible. Similarly, Coverdale’s 1535 Bible reads saydest for Psalm 89:19 (rather than the saidst of the 1611 King James Bible); see the citations in the Oxford English Dictionary under the variant spellings for said(e)st listed under the verb say. The OED also cites the following example from the middle of the 1800s:
The occasional 19th-century use of saidest argues that the original occurrence of saidest in 𝓟 for Alma 11:25 could be an instance of dialectal overlay. But since saidest was possible in Early Modern English, the critical text will accept such usage. There is only one other instance of said(e)st in the Book of Mormon text, and that one reads saidst in the earliest text (but said in the early editions from 1837 through 1858):
The past-tense modal verbs should and would provide additional examples of textual variation for the second person singular ending -(e)st. For discussion, see under 1 Nephi 20:5. There the argument is that we should in each case follow the earliest textual sources in determining whether the ending should be -est or -st. We will follow the same here in Alma 11:25 with respect to the form saidest.
Summary: Restore the form saidest in Alma 11:25, the earliest reading in 𝓟, rather than the expected King James saidst (the 1830 typesetter’s emendation towards the biblical style).