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.

In what statement of the Scripture was Abraham's obedience really implied?
What is the character of a child who will not listen to his father's instruction?
How does Paul give expression to this hope?
What will He say to those on His right hand?
In what condition did David expect to rise?
What is one evidence that one has a knowledge of God?
How does the prophet again speak of this time?

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