one be ordained among you, and to him will I give power that he shall break bread and bless it and give it unto the people of my church, unto all those who shall believe and be baptized in my name” (3 Nephi 18:5).
“All covenants, contracts, bonds, obligations, oaths, vows, performances, connections, associations, or expectations, that are not made and entered into and sealed by the Holy Spirit of promise, of him who is anointed, both as well for time and for all eternity, and that too most holy, by revelation and commandment through the medium of mine anointed, whom I have appointed on the earth to hold this power (and I have appointed unto my servant Joseph to hold this power in the last days, and there is never but one on the earth at a time on whom this power and the keys of this priesthood are conferred), are of no efficacy, virtue, or force in and after the resurrection from the dead; for all contracts that are not made unto this end have an end when men are dead. Behold, mine house is a house of order, saith the Lord God, and not a house of confusion. Will I accept of an offering, saith the Lord, that is not made in my name? Or will I receive at your hands that which I have not appointed? And will I appoint unto you, saith the Lord, except it be by law, even as I and my Father ordained unto you, before the world was?” (D&C 132:7-11).
Power or authority is delegated from the one person to others of his choosing, since it is not practical for one person to perform a given ordinance for many members scattered throughout the world.
“Thus saith the Lord God, the Mighty One of Israel: Behold, I say unto you, my servant Edward, that you are blessed, and your sins are forgiven you, and you are called to preach my gospel as with the voice of a trump; And I will lay my hand upon you by the hand of my servant Sidney Rigdon, and you shall receive my Spirit” (D&C 36:1-2).
Ultimately, all authority comes from the Savior.
“Go ye into all the world, preach the gospel to every creature, acting in the authority which I have given you, baptizing in the name of the Father, and of the Son, and of the Holy Ghost” (D&C 68:8).
“And now behold, these are the words which ye shall say, calling them by name, saying: Having authority given me of Jesus Christ, I baptize you in the name of the Father, and of the Son, and of the Holy Ghost. Amen” (3 Nephi 11:24-5).
“The person who is called of God and has authority from Jesus Christ to baptize, shall go down into the water with the person who has presented himself or herself for baptism, and shall say, calling him or her by name: Having been commissioned of Jesus Christ, I baptize you in the name of the Father, and of the Son, and of the Holy Ghost. Amen” (D&C 20:73).