Ordinances and Covenants are Essential

Doctrine and Covenants 54:4-6

4 And as the covenant which they made unto me has been broken, even so it has become void and of none effect.

5 And wo to him by whom this offense cometh, for it had been better for him that he had been drowned in the depth of the sea.

6 But blessed are they who have kept the covenant and observed the commandment, for they shall obtain mercy. - Doctrine and Covenants 54:4-6

Doctrine and Covenants 132:7

7 And verily I say unto you, that the conditions of this law are these: 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.

Doctrine and Covenants 132:7

Doctrine and Covenants 133:57-60

57 And for this cause, that men might be made partakers of the glories which were to be revealed, the Lord sent forth the fulness of his gospel, his everlasting covenant, reasoning in plainness and simplicity—

58 To prepare the weak for those things which are coming on the earth, and for the Lord’s errand in the day when the weak shall confound the wise, and the little one become a strong nation, and two shall put their tens of thousands to flight.

59 And by the weak things of the earth the Lord shall thresh the nations by the power of his Spirit.

60 And for this cause these commandments were given; they were commanded to be kept from the world in the day that they were given, but now are to go forth unto all flesh—  Doctrine and Covenants 133:57-60

Doctrine and Covenants 35:24

24 Keep all the commandments and covenants by which ye are bound; and I will cause the heavens to shake for your good, and Satan shall tremble and Zion shall rejoice upon the hills and flourish;

Doctrine and Covenants 35:24