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.

What is sin?
Did Christ, while on earth, keep the Sabbath?
What Christian grace are we exhorted to exercise in our expectant longing for this event?
What will then take place?
In what respect is the reaping of God's people to differ from their sowing?
What did the prophet Isaiah predict of Christ?
What precious promise has God made to His children?

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