On January 19th, 1841, the Lord gave through Joseph the only significant revelation to the saints during the Nauvoo period. It is what we now number as D&C 124. Among other critical direction given (the conditions by which they would not be driven out of Nauvoo), He gave the following concerning Hyrum in verses 91-96:
Let my servant William be appointed, ordained, and anointed,
as counselor unto my servant Joseph,
in the room of my servant Hyrum,
That my servant Hyrum may take the office of Priesthood and Patriarch,
which was appointed unto him by his father,
and also by right;
that from henceforth
he shall hold the keys of THE Patriarchal Blessings [or, the blessings of the Patriarchs]
upon the heads of all my people,
that whoever he blesses
shall be blessed,
and whoever he curses
shall be cursed;
that whatsoever he shall bind on earth
shall be bound in heaven;
and whatsoever he shall loose on earth
shall be loosed in heaven.
And from this time forth
I appoint unto him that he may be:
and a seer,
and a revelator
unto my church,
as well as my servant Joseph;
that he may act in concert also with my servant Joseph;
and that he shall receive counsel from my servant Joseph,
who shall show unto him the keys
whereby he may ask and receive,
and be crowned
with the same blessing,
and gifts of the priesthood,
that once were put upon him that was my servant Oliver Cowdery;
that my servant Hyrum may bear record
of the things which I shall show unto him,
that his name may be had in honorable remembrance
from generation to generation,
forever and ever.
By continuing the office of Presiding Patriarch, the generations of men in our LDS Church "had [Hyrum's] name in [semi-]honorable remembrance" for four generations. The LDS Church has never, however, acknowledged Hyrum as the Lord did: having Himself designated Hyrum as the second prophet to the Church, Hyrum also having been elected co-president with Joseph. His epistle to the church is not to be even found on LDS.org--it really should have been included in our Doctrine and Covenants, as some of Joseph's were.
As noted in Preserving the Restoration:
One of the last signs indicating the end of the gentiles was the passing of Eldred Smith in 2013, and with him the office of Patriarch to the church. Only one thing now remains. God must send a witness to be the final required “sign” sent to declare God’s intention to begin something new.The excommunication of the author of the book, as a messenger sent by the Lord to minister to believing LDS Mormons was directed by members of the LDS Quorum of the 12, Seventies, and First Presidency itself (by refusing the appeal) and constituted part of the final "sign" referenced.
The content, times, and locations for the ten-part talk that the author claims Christ directed him to give served as the basis for the Lord's "set[ting] His hand the second time to restore His people from their lost and fallen state." (2 Nephi 25:17) Two additional witnesses of this claim, having each been directly told so by the Lord Himself, are included in the book--one at the beginning and one at the end.
I add my own witness that the Lord has told me in His own voice that the message in Preserving the Restoration is His and did not originate with the author of the talk and book. I believe it is a fulfillment of the words Christ promised in 3 Nephi 21:11 to give:
Therefore it shall come to pass that whosoever will not believe in My words, who am Jesus Christ, which the Father shall cause him to bring forth unto the Gentiles, and shall give unto him power that he shall bring them forth unto the Gentiles, (it shall be done even as Moses said) they shall be cut off from among my people who are of the covenant.This is the commandment (2 Nephi 9:23-24):
And if they will not repent and believe in [Christ's] name, and be [re]baptized in His name, and endure to the end, they must be damned; for the Lord God, the Holy One of Israel, has spoken it.This is precisely what Joseph and Hyrum invited us to do. By hearing the invitation given through them (but not by following them), we "have them in honorable remembrance." But the time for idolatry and worship of men is past--it will utterly damn us as LDS Mormons if we do not repent of it. Christ only is to be worshiped, and His words, by whomever they are given, must be hearkened to.