“Alma and the People of the Lord Were Apprised”
Joseph F. McConkie, Robert L. Millet
More specifically, Alma and his people were “warned of the Lord that the armies of king Noah would come upon them” (Mosiah 23:1; italics added).
Doctrinal Commentary on the Book of Mormon, Vol. 2
References
Mosiah 18:34, 23:1