As discussed under 1 Nephi 22:4, Oliver Cowdery frequently mixed up whether and whither. Here in Alma 29:4, he initially wrote the correct whether in 𝓞, but then he emended it to the incorrect whither. Almost immediately he overwrote the e with an i (there is no change in the level of ink flow for the overwriting). Oliver copied the word as whither into 𝓟, but John Gilbert (the 1830 typesetter) emended it in 𝓟 to the correct whether.
For this instance of whether, there has been no variation in the printed history of the text since whether is obviously correct. It is also supported by the invariant use of whether later on in this verse (“whether it be unto salvation or unto destruction”) and in the next verse (“whether he desireth good or evil”).
Summary: Maintain in Alma 29:4 the first instance of whether rather than the whither that Oliver Cowdery substituted for it in the manuscripts.