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?
How may we determine the truthfulness of any doctrine ?
What is the first which He took away?
When are the saints to be like Jesus?
24. What psalms seem to have been written especially for the comfort and encouragement of God's people during the time of the seven last plagues?
Does God willingly afflict the children of men?
How does God anticipate the needs of His children?

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