Doctrine & Covenants 59:10-12

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