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 are we exhorted by, the prophet to seek?
In whose name should everything be done?
After receiving a knowledge of the truth, what must one do in order to be sanctified by it?
What does Christ say of that servant who, when He comes, is found giving \"meat in due season\"?
From what is He able to keep us?
What reason is given in the commandment for keeping the Sabbath day holy?
What promise, through the prophet Malachi, does the Lord make concerning Elijah?

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