D&C 59:2a-3a "Wherefore I give unto them a commandment, saying thus: Thou shalt love the Lord thy God, with all thy heart, with all thy might, mind, and strength; and in the name of Jesus Christ thou shalt serve him.
Thou shalt love thy neighbor as thyself.
Thou shalt not steal; neither commit adultery, nor kill, nor do anything like unto it.
Thou shalt thank the Lord thy God in all things.
Thou shalt offer a sacrifice unto the Lord thy God in righteousness; even that of a broken heart and a contrite spirit.
And that thou mayest more fully keep thyself unspotted from the world, thou shalt go to the house of prayer and offer up thy sacraments upon my holy day; for verily this is a day appointed unto thee to rest from thy labors, and to pay thy devotions unto the Most High; nevertheless thy vows shall be offered up in righteousness on all days, and at all times; but remember that on this, the Lord's day, thou shalt offer thine oblations, and thy sacraments, unto the Most High, confessing thy sins unto thy brethren, and before the Lord. And on this day thou shalt do none other thing, only let thy food be prepared with singleness of heart, that thy fasting may be perfect; or in other words, that thy joy may be full."

Which commandment can we ignore?