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.

13. What did John the Baptist say to the Pharisees and Sadducees when he saw them come to his baptism?
What followed immediately after the gaoler and his family had accepted Christ as their Saviour?
While God is merciful, does this clear the guilty?
Why did the Lord destroy Sodom?
What is one of the offices of the moral law?
Through whom did God create the world?
How does James say the rich have treated the just?

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