"If a man gets a fulness of the priesthood of God, he has to get it in the same way that Jesus Christ obtained it, and that was by keeping all the commandments and obeying all the ordinances of the house of the Lord. ...
"All men who become heirs of God and joint-heirs with Jesus Christ will have to receive the fulness of the ordinances of his kingdom; and those who will not receive all the ordinances will come short of the fulness of that glory."
(History of the Church, 5:424; spelling modernized; from a discourse given by Joseph Smith on June 11, 1843, in Nauvoo, Illinois; reported by Wilford Woodruff and Willard Richards.)

"... Ordinances instituted in the heavens before the foundation of the world, in the priesthood, for the salvation of men, are not to be altered or changed. All must be saved on the same principles.
(History of the Church, 5:42325, 427; paragraph divisions altered; from a discourse given by Joseph Smith on June 11, 1843, in Nauvoo, Illinois; reported by Wilford Woodruff and Willard Richards.)

Doctrine and Covenants 1:
14 And the arm of the Lord shall be revealed; and the day cometh that they who will not hear the voice of the Lord, neither the voice of his servants, neither give heed to the words of the prophets and apostles, shall be cut off from among the people;
15 For they have strayed from mine ordinances, and have broken mine everlasting covenant;
16 They seek not the Lord to establish his righteousness, but every man walketh in his own way, and after the image of his own god, whose image is in the likeness of the world, and whose substance is that of an idol, which waxeth old and shall perish in Babylon, even Babylon the great, which shall fall.

The power, glory, and blessings of the priesthood could not continue with those who received ordination only as their righteousness continued, for Cain also being authorized to offer sacrifice but not offering it in righteousness, therefore he was cursed. It signifies then, that the ordinances must be kept in the very way God has appointed, otherwise their priesthood will prove a cursing instead of a blessing. (Joseph Smith, WOJS)

5.The earth also is defiled under the inhabitants thereof; because they have transgressed the laws, changed the ordinance, broken the everlasting covenant.
6.Therefore hath the curse devoured the earth, and they that dwell therein are desolate: therefore the inhabitants of the earth are burned, and few men left.
(Isaiah 24:5-6)

Doctrine and Covenants 130:
20 There is a law, irrevocably decreed in heaven before the foundations of this world, upon which all blessings are predicated--
21 And when we obtain any blessing from God, it is by obedience to that law upon which it is predicated.

Alma 34:
13 Therefore, it is expedient that there should be a great and last sacrifice, and then shall there be, or it is expedient there should be, a stop to the shedding of blood; then shall the law of Moses be fulfilled; yea, it shall be all fulfilled, every jot and tittle, and none shall have passed away.
14 And behold, this is the whole meaning of the law, every whit pointing to that great and last sacrifice; and that great and last sacrifice will be the Son of God, yea, infinite and eternal.
15 And thus he shall bring salvation to all those who shall believe on his name; this being the intent of this last sacrifice, to bring about the bowels of mercy, which overpowereth justice, and bringeth about means unto men that they may have faith unto repentance.
16 And thus mercy can satisfy the demands of justice, and encircles them in the arms of safety, while he that exercises no faith unto repentance is exposed to the whole law of the demands of justice; therefore only unto him that has faith unto repentance is brought about the great and eternal plan of redemption.

Doctrine and Covenants 76:
22 And now, after the many testimonies which have been given of him, this is the testimony, last of all, which we give of him: That he lives!
23 For we saw him, even on the bright hand of God; and we heard the voice bearing record that he is the Only Begotten of the Father--
24 That by him, and through him, and of him, the worlds are and were created, and the inhabitants thereof are begotten sons and daughters unto God.
25 And this we saw also, and bear record, that an angel of God who was in authority in the presence of God, who rebelled against the Only Begotten Son whom the Father loved and who was in the bosom of the Father, was thrust down from the presence of God and the Son,
26 And was called Perdition, for the heavens wept over him--he was Lucifer, a son of the morning.