It is not hard to imagine that this teaching originated with Alma. Yet, five years prior, Alma was not quite sure how or when the Lord would manifest himself unto his people. At that time, he said, the time is not far distant that the Redeemer liveth and cometh among his people. Behold, I do not say that he will come among us at the time of his dwelling in his mortal tabernacle; for behold, the Spirit hath not said unto me that this should be the case. Now as to this thing I do not know (Alma 7:7-8). Apparently, Alma subsequently learned through the Spirit that he would appear after his resurrection.
This time among the Nephites was a time to prepare their hearts to receive the word which should be taught among them at the time of his coming (v. 16). The doctrine of His impending visit seems to be essential to that preparation. Appropriately, this the people did hear with great joy and gladness.