By what authority was Sunday Sabbath-keeping instituted?

Answer

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

28. BY what miracle and phenomenon in nature did God indicate the character of the deed which was being committed?
How long was the Sabbath to be a sign of the true God?
Of what did Christ say the Son of man is Lord?
What may be known with equal certainty when these signs have been seen?
How did Christ speak of the gathering of the Gentiles?
When will the resurrection of the just occur?
In what work are angels engaged?

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