By what authority was Sunday Sabbath-keeping instituted?

Answer

By the authority of the Catholic Church. See page 131.

9. What expressions in the prophecy of Joel seem to imply a double fulfilment of this outpouring of the Spirit?
Where were the Ten Commandments placed?
What is it that makes a thing holy?
What comforting promise has God made concerning the sleeping saints?
With what announcement does the sixth trumpet close?
How does God regard the afflicted?
To whom did Jesus first send the twelve disciples?

Questions & Answers are from the book Bible Readings for the Home Circle