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 way is this comparison further explained?
How necessary is the experience of sanctification?
What is the fear of the Lord declared to be?
How far-reaching is God's ability to reveal the future?
How did this change in observance of days come about, suddenly or gradually?
25. Since the Sunday Sabbath originated with the Roman power (the beast), to whom will men yield deference to compulsory Sunday laws?
What encouragement is given to heed this message?

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