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 leads sinners to repentance?
What exhortation is based on the fact that God has forgiven us?
How did Abraham respond to this command?
How is the conflict between Christ and Satan described?
To whom, then, should its observance be rendered?
When John the Baptist was asked if he were Elijah, what did he say?
Whom will they be like?

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