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.

How did Christ make it clear to them that the Scriptures testify of Him?
How was the prophecy given?
How many are concerned in the judgment?
What did Christ say of worship based upon the commandments of men?
With what do these trumpets deal?
In whose name did Christ teach us to pray?
How much did this promise comprehend?

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