In this passage Oliver Cowdery accidentally dropped the plural s from things as he copied from 𝓞 into 𝓟. In the original text, “whatsoever things” is just as frequent as “whatsoever thing”: there are 11 occurrences of the plural and 11 of the singular. But more importantly, whenever the text refers to the gathering together of supplies for a trip, we otherwise get only the plural “whatsoever things”:
Like 1 Nephi 18:6, the plural “whatsoever things” is extant in 𝓞 for 1 Nephi 16:11.
Summary: Restore in 1 Nephi 18:6 the plural “whatsoever things” of the original manuscript; such plural usage is found elsewhere in the text when referring to preparations for a journey.