The Aaronic Priesthood
Doctrine and Covenants 13:1
1 Upon you my fellow servants, in the name of Messiah I confer the Priesthood of Aaron, which holds the keys of the ministering of angels, and of the gospel of repentance, and of baptism by immersion for the remission of sins; and this shall never be taken again from the earth, until the sons of Levi do offer again an offering unto the Lord in righteousness.
President Joseph Fielding Smith wrote:
“We may be sure that the Aaronic Priesthood will never be taken from the earth while mortality endures, for there will always be need for temporal direction and the performance of ordinances pertaining to ‘the preparatory Gospel’ [D&C 84:26].”
(Church History and Modern Revelation, 2 vols. , 1:62.)