This statement is very similar to Ammon’s statement in his own declaration about the success of the missionary work of the sons of Mosiah. See Alma 26:11. In this verse and in the declaration by Ammon, the word “joy” is used. For both of these men, the work of the Lord leads to joy. See the discussion following 2 Nephi 2:25 in this commentary for a discussion of the meaning of joy in the Book of Mormon.
Brown sees this verse as intimately connected with Alma’s conversion experience. The aspect of joy is a certain touchpoint, but Brown suggests that the concept of missionary work also flows from that original experience:
“Similarly, in his personal recounting Alma told his son Helaman that from the time of his three-day ordeal until that moment, “I have labored without ceasing, that I might bring souls unto repentance; that I might bring them to taste of the exceeding joy of which I did taste” (Alma 36:24). He continued by speaking metaphorically of his success in his missionary endeavors as if it were fruit of agricultural labors:
“The Lord doth give me exceedingly great joy in the fruit of my labors; For because of the word which he has imparted unto me, behold, many have been born of God, and have tasted as I have tasted, and have seen eye to eye as I have seen” (vv 25-26; compare Alma 29:13-15). (S. Kent Brown. “Alma’s Conversion: Reminiscences in His Sermons.” In Monte S. Nyman and Charles D. Tate, Jr., eds., Alma, the Testimony of the Word [Provo: BYU Religious Studies Center, 1992], 149 - 150.)