Here Oliver Cowdery initially wrote Alma sayest in 𝓞; somewhat later, probably after reading back the text to Joseph Smith, he crossed out sayest and supralinearly inserted the correct saith (the level of ink flow for the correction is somewhat heavier). Here Oliver’s initial sayest was probably influenced by the use of the -est ending in the following clause: “believest thou that there is a God”. An additional instance of this same error, but left uncorrected in 𝓞, is found later on in the text:
In this second instance, Oliver corrected sayest to saith (spelled as sayeth) when he copied from 𝓞 into 𝓟. For both these passages in the book of Alma, the historical present tense was changed by Joseph to said in his editing for the 1837 edition, but saith will be restored in the critical text. In a number of other cases, Oliver initially replaced the third person singular ending -(e)th with the second person singular -(e)st. For a list, see under 1 Nephi 11:2; also see the general discussion under infl al endings in volume 3.
Summary: Restore the historical present-tense saith in Alma 30:37, the corrected reading in 𝓞.