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 revealed in the gospel?
How are the present effects and future results of chastisement contrasted?
What was Messiah to do during the seventieth week?
While God is merciful, does this clear the guilty?
18. Before giving the law at Sinai, what did God say because some of the people went out to gather manna on the seventh day?
What is the purpose of the Federal Council of the Churches of Christ in America?
What warning has Christ given that we might not be taken by surprise by this great event?

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