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 do the heavens declare?
With whom did the prophet Isaiah say Christ would make His grave?
What first attracted the prophet's attention?
What work did Daniel see finally assigned to the saints?
Whom are all called upon to worship?
What will the Lord he to His people at this time?
Of what will the saints speak?

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