God prior to this time, had given revelation to this youth, on many occasions. The first one that he gave to him was in the spring of 1820, before Joseph Smith was of the age of fifteen. Then a wonderful revelation was given to him, the first one he ever received. In a great and glorious open vision, in answer to his prayers, there was the manifestation of two of the great personages in the heavens-not angels, not messengers, but two persons that hold the keys of authority over all the creations of the universe. Who were they? God the Eternal Father and his Son Jesus Christ, through whom God the Father made the worlds!
Journal of Discourses 21:308 (September 19, 1880). - Joseph Smith Jr.'s First Vision
Journal of Discourses/Volume 21/A Double Birthday—The Authority of the Priesthood, etc.