By what authority was Sunday Sabbath-keeping instituted?

Answer

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

18. When asked by the rich young man the conditions of eternal life, to what did Jesus direct his attention?
When Pilate heard that Christ was from Galilee, what did he do?
Concerning what subject ought we to be informed?
To whom do the things which have been revealed belong ?
What becomes of man's thoughts at death?
How does God regard the afflicted?
What did Christ say would be the experience of His people in this world?

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