I hate, I despise your feast days, and I will not smell in your solemn assemblies. Though ye offer me burnt offerings and your meat offerings, I will not accept them: neither will I regard the peace offerings of your fat beasts. Take thou away from me the noise of thy songs; for I will not hear the melody of thy viols. But let judgment run down as waters, and righteousness as a mighty stream.
For verily this is a day appointed unto you to rest from your 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.
Doctrine and Covenants 59:9-13