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.

For what purpose was Christ manifested?
What relation does faith bear to knowledge?
And what besides a mere belief in the truth is necessary?
Did Christ know beforehand the treatment He was to receive?
What work did Daniel see finally assigned to the saints?
While God is merciful, does this clear the guilty?
Whom does God comfort?

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