Gen 4:2 And again, she bore his brother Abel. Now Abel was a keeper of sheep, and Cain a worker of the ground.
Gen 4:4 and Abel also brought of the firstborn of his flock and of their fat portions. And the Lord had regard for Abel and his offering,

Gen 4:8 Cain spoke to Abel his brother. And when they were in the field, ^ Cain rose up against his brother Abel and killed him.
Gen 4:9 Then the Lord said to Cain, “Where is Abel your brother?” He said, “I do not know; am I my brother’s keeper?”

Gen 4:25 And Adam knew his wife again, and she bore a son and called his name Seth, for she said, “God has appointed for me another offspring instead of Abel, for Cain killed him.”
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