The 1837 edition dropped the adjective own before hands. The 1908 RLDS text restored the own, the reading of the printer’s manuscript. This 1837 change appears to be accidental since the text has 14 other occurrences of “own hands” and none of these have ever lost the own throughout the textual history. Moreover, Joseph Smith did not mark the deletion of this own in his editing of 𝓟 for the 1837 edition.
When the verb is labor, we normally have “own hands” (seven times, including here in Alma 1:3), but it is also possible for the own to be lacking (two times, each marked below with an asterisk):
For each case of “to labor with one’s (own) hands”, we follow the earliest textual sources.
Summary: Restore in Alma 1:3 the own that the 1837 edition accidentally dropped from “they ought not to labor with their own hands”.