Hebrews 8:4

Now if perfection had been reached through the Levitical priesthood -- for on it as a basis even the law was enacted for the people-- what further need would there have been of appointing a different priest, with the rank of Melchizedek, instead of designating one with the rank of Aaron?

By faith Abel offered a sacrifice more acceptable to God than Cain did, for by it he was approved as an upright man, since God approved him for the offering he made; and by it he still continues to speak, though dead.