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.

To how many is the Lord good?
How was Christ's first advent to be heralded?
What answer did he return when asked concerning his mission?
What is the strength of sin?
What is it that makes a thing holy?
In His first recorded discourse, what did Christ say of the law?
Who has everlasting life?

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