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 instruction did He emphasize the importance of keeping the law?
BY whom was the Ten Commandment law proclaimed?
How does the Lord, through the prophet Isaiah, indicate what is true Sabbath-keeping?
With what is God's seal connected?
What deliverance will God finally bring to His people in this controversy?
After whose body will these resurrected ones be fashioned?
Under what condition does the Lord not hear prayer?

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