Hebrews 11:4

By faith Abel offered up to God a more acceptable sacrifice than Cain, through which he received the witness that he was righteous, God witnessing to his gifts: and through it he having died is still speaking.

Hebrews 9:22

And according to the law, almost all things are purified by blood; and without the shedding of blood there is no remission.

1 Peter 1:19-20

but by the precious blood of Christ, as a lamb without blemish and spotless:

Revelation 13:8

And all those who dwell upon the earth, whose name has not been written in the book of life of the Lamb that was slain from the foundation of the world, will worship him.

Treasury of Scripture Knowledge

Summary

And Abel, he also brought of the firstlings of his flock and of the fat thereof. And the LORD had respect unto Abel and to his offering:

Bible References

The firstlings

Hebrews 9:22
And according to the law, almost all things are purified by blood; and without the shedding of blood there is no remission.
1 Peter 1:19
but by the precious blood of Christ, as a lamb without blemish and spotless:
Revelation 13:8
And all those who dwell upon the earth, whose name has not been written in the book of life of the Lamb that was slain from the foundation of the world, will worship him.