How early was this sacrificial system known?

Answer

"By faith Abel offered unto God a more excellent sacrifice than Cain, by which he obtained witness that he
was righteous, God testifying of his gifts." Heb. 11: 4. See Gen. 4: 3-5; 8: 20.

In what condition are all before they are quickened with Christ?
What does God desire to teach the children?
What is the fear of the Lord declared to be?
Of what else does God say He gave the Sabbath to His people to be a sign, or reminder?
By what method of reasoning did Christ justify acts of mercy on the Sabbath day?
Did they observe it after His resurrection?
What relation do all sustain to God?

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