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 condition are all men?
What first attracted the prophet's attention?
Why is the carnal mind enmity against God?
What was the Lord's covenant which they were to keep as their part of this covenant?
What example did Christ set in Sabbath observance?
In view of this fact, what does Christ tell us to do?
What is promised to the willing and obedient?

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