One of the Eight Witnesses of the Book of Mormon (see D&C 16:Intro.) and among the six original members of Church of Jesus Christ of Latter-day Saints.
D&C 30:5-6 given at Fayette, New York. Oliver Cowdery had been given power to build up the church among the Lamanites.
See D&C 30: 5-8 served with Oliver Cowdery.