President Joseph and I went to B[enjamin] F. Johnsons to sleep. Before we retired the President gave Brother Johnson and wife some instructions on the priesthood. He put his hand on my knee and says "your life is hid with Christ in God, and so is many others." Addressing Benjamin says he "nothing but the unpardonable sin can prevent him (me) from inheriting eternal glory for he is sealed up by the power of the priesthood unto eternal life having taken the step which is necessary for that purpose." He said that except a man and his wife enter into an everlasting covenant and be married for eternity while in this probation by the power and authority of the Holy priesthood they will cease to increase when they die (i.e. they will not have any children in the resurrection), but those who are married by the power and authority of the priesthood in this life and continue without committing the sin against the Holy Ghost will continue to increase and have children in the celestial glory. The unpardonable sin is to shed innocent blood or be accessory thereto. All other sins will be visited with judgement in the flesh and the spirit being delivered to the buffetings of satan untill the day of the Lord Jesus." I feel desirous to be united in an everlasting convenant to my wife and pray that it may soon be. President J[oseph] said that the way he knew in whom to confide, God told him in whom he might place confidence. He also said that in the celestial glory there was three heavens or degrees, and in order to obtain the highest a man must enter into this order of the priesthood and if he don't he can't obtain it. He may enter into the other but that is the end of his kingdom he cannot have increase.
[This is the source for D&C 131]
[Source: George D. Smith, An Intimate Chronicle; The Journals of William Clayton, Signature Books in association with Smith Research Associates, Salt Lake City, 1995, http://bit.ly/WilliamClayton]