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 did Christ say to the Jews concerning the study of the Scriptures?
Of whom did Christ say the Scriptures testify?
For what purpose is the mystery of the gospel made manifest?
After creating man, what did God say?
What statement did Paul make concerning his faith and manner of worship?
What has this firm trust in Jesus led many to do?
What did Paul say regarding our duty to the poor?

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