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.

Who alone comprehends the things of God?
In contrast with the pride and self-exaltation exhibited by Satan, what spirit did Christ manifest?
How is eternal life bestowed?
Who does the apostle say saw Christ after He was risen?
What question does Job ask and answer?
Is there any limit to God's ability to help?
Who else appeared on this occasion?

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