Revelation through Joseph Smith, Kirtland, Ohio, March 8, 1831. History of the Church 1:166.
1 Behold, it is expedient in me that my servant John should write and keep a regular history, and assist you, my servant Joseph, in transcribing all things which shall be given you, until he is called to further duties.
2 Again, verily I say unto you that he can also lift up his voice in meetings, whenever it shall be expedient.
3 And again, I say unto you that it shall be appointed unto him to keep the church record and history continually; for Oliver Cowdery I have appointed to another office.
4 Wherefore, it shall be given him, inasmuch as he is faithful, by the Comforter, to write these things. Even so. Amen.