1 Samuel 18:29

Treasury of Scripture Knowledge

And Saul was yet the more afraid of David; and Saul became David's enemy continually.

Saul was afraid of David, because Yahweh was with him, and was departed from Saul.

The wicked plots against the just, and gnashes at him with his teeth.

Then I saw all the labor and achievement that is the envy of a man's neighbor. This also is vanity and a striving after wind.

You believe that God is one. You do well. The demons also believe, and shudder.

Abel also brought some of the firstborn of his flock and of its fat. Yahweh respected Abel and his offering,

So from that day forward they took counsel that they might put him to death.

unlike Cain, who was of the evil one, and killed his brother. Why did he kill him? Because his works were evil, and his brother's righteous.