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.

Upon what basis does the reward come to one who works?
Why was Christ's preaching so impressive?
In this covenant with Israel, what obligation was imposed upon the people?
18. Knowing that the unbelieving Jews would still cling to their false ideas respecting the Sabbath, pray?
What class only have part in the first resurrection?
To whose authority are the angels subject?
What promise was made to Abraham concerning the land?

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