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 declared to be?
11. How is the closing work of the gospel under the outpouring of the Spirit described by the Revelator?
How are those described who heed this warning?
How, then, did the Lord prove the people (verse 4) whether they would keep His law, or not?
What besides creation were Israel to remember when they kept the Sabbath?
What will the world be doing when Christ comes?
What will finally he the privilege of God's children?

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