Here the 1874 RLDS edition accidentally replaced the preposition to with in, perhaps in anticipation of the following phrase, “in humility”. Another possible influence is that the typesetter may have expected “let it bring you down in the dust”, as in these two passages:
Here in Alma 42:30, the 1908 RLDS edition restored the original preposition to. The critical text will follow the earliest extant reading, “but let it bring you down to the dust in humility” (the reading in 𝓟).
Summary: Accept in Alma 42:30 the use of the preposition to in “but let it bring you down to the dust”, the reading of the earliest textual sources.