I believe that we should rest on Sunday.

"Remember the sabath day, to keep it holy. Six days shalt thou labor, and do all thy work: But the seventh day is the sabbath of the Lord thy God: in it thou shalt not do any work, thou, nor thy son, nor thy daughter, thy manservant, nor thy maidservant, nor thy cattle, nor thy stranger that is within thy gates; For in six days the Lord made heaven and earth, the sea, and all that in them is, and rested the seventh day: wherefore the Lord blessed the sabbath day, and hallowed it."
- Exodus 20:8-11

Elder L. Tom Perry said:

"As we consider the Sabbath and the sacrament in our own lives, there appears to be three things the Lord requires of us: first, to keep ourselves unspotted from the world; second, to go to the house of prayer and offer up our sacraments; and third, to rest from our labors."

"For verily this is a day appointed unto you to rest from your labors, and to pay thy devotions unto the Most High"
- Doctrine and Covenants 59:10