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 accompanies repentance?
What great truth was then stated?
How is this expressed by Mark?
How did David express himself on this point?
What promise has God made to bereaved mothers?
Where is this city, and what is it called?
What is the measurement of the city?

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