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 is all Scripture profitable?
Because some thought He had come to destroy the law, what did Christ say?
What will He say to those on His right hand?
With what do these trumpets deal?
If an answer does not come at once, what should we do?
When she persisted in her request, and fell down to worship Him, what did He say?
What did John see concerning this city?

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