Joseph Smith
“The doctrine or sealing power of Elijah is as follows:If you have power to seal on earth and in heaven, then we should be wise. The first thing you do, go and seal on earth your sons and daughters unto yourself, and yourself unto your fathers in eternal glory, and go ahead, and not go back, but use a little wisdom, and seal all you can, and when you get to heaven tell your Father that what you seal on earth should be sealed in heaven, according to his promise. I will walk through the gate of heaven and claim what I seal, and those that follow me and my counsel.” (Teachings of the Prophet Joseph Smith, p. 340)
Boyd K. Packer
"That sacred sealing power is with the Church now. Nothing is regarded with more sacred contemplation by those who know the significance of this authority. Nothing is more closely held. There are relatively few men who have been delegated this sealing power upon the earth at any given time—in each temple are brethren who have been given the sealing power. No one can get it except from the prophet, seer, and revelator and President of The Church of Jesus Christ of Latter-day Saints.
"A clear statement follows regarding the sealing power as binding on all that we do for the living and the dead.
"’Whenever the fulness of the gospel is on earth, the Lord has agents to whom he gives power to bind on earth and seal eternally in the heavens (Matt. 16:19; Matt. 18:18; Hel. 10:3-10; D&C 132:46-49.)
"’All things that are not sealed by this power have an end when men are dead. Unless a baptism has this enduring seal, it will not admit a person to the celestial kingdom; unless an eternal marriage covenant is sealed by this authority, it will not take the participating parties to an exaltation in the highest heaven within the celestial world.
"’All things gain enduring force and validity because of the sealing power. So comprehensive is this power that it embraces ordinances performed for the living and the dead, seals the children on earth up to their fathers who went before, and forms the enduring patriarchal chain that will exist eternally among exalted beings’ (Bruce R. McConkie, Mormon Doctrine, 2d ed., Salt Lake City: Bookcraft, 1966, p. 683).
“In the Church we hold sufficient authority to perform all of the ordinances necessary to redeem and to exalt the whole human family. And, because we have the keys to the sealing power, what we bind in proper order here will be bound in heaven. Those keys—the keys to seal and bind on earth, and have it bound in heaven—represent the consummate gift from our God. With that authority we can baptize and bless, we can endow and seal, and the Lord will honor our commitments.” (Ensign, Feb. 1995, p. 32)