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.

How is eternal life bestowed?
How does the Revelator describe this satanic desire to destroy Christ?
Why were the Sacred Writings given?
Have the worthies of old gone to their reward?
How many of these beings did John see around the throne?
22. When surrounded by the Syrian host, what did Elisha say, and for what did he pray, to encourage his frightened servant?
What promise is made to those that mourn?

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