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 instruction did the Apostle Peter give concerning the Gentiles who had believed?
What blessed assurance is given all believers in Christ?
What inspired Prayer sets the standard of Christian experience?
What distinct purpose did Christ have in giving Himself for the church?
What, according to prophecy, was to be Christ's attitude toward the law?
To whom does the Sabbath belong?
Why did the unjust judge answer the widow's prayer?

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