Genesis 4:25

And Adam knew his wife again; and she bare a son, and called his name Seth [lit: appointed]: For God, [said she,] hath appointed me another seed instead of Abel, whom Cain slew.

Genesis 4:23

And Lamech said unto his wives, Adah and Zillah, Hear my voice; ye wives of Lamech, hearken unto my speech: for I have slain [killed a man for wounding me] a man to my wounding, and a young man to my hurt [for hurting me].

Genesis 4:8

And Cain talked with Abel his brother: ["saying, let us go out into the field] and it came to pass, when they were in the field, that Cain rose up against Abel his brother, and slew him.