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 prophecy are Christ's life, suffering, and death touchingly foretold?
Whom did Moses say the Lord would raise up?
Through whom is the reconciliation received?
What is the foundation of faith?
What is said of his mother and his grandmother?
How is the conflict between Christ and Satan described?
27. What wonderful promises are made to those who thus minister to the wants and distresses of others?

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