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.

After the Flood, what came in consequence of further apostasy from God?
From what time does David say he himself was taught?
After she became queen of Persia, how did Esther show her integrity to God?
How is the law further described?
At His ascension, how did the angels say Christ would come again?
Are the angels interested in the plan of salvation?
When will immortality be conferred upon the saints?

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