After the death of Abel at the hand of Cain, Adam and Eve have a third son, Seth.
Tragedy strikes early in the life of Adam and Eve after being expelled from the Garden. They had two sons, Cain and Abel, but then Cain grew jealous and killed his brother.
This created a void in the family, which was soon occupied by a new son.
Adam again had intercourse with his wife, and she gave birth to a son whom she called Seth. “God has granted me another offspring in place of Abel,” she said, “because Cain killed him.” To Seth, in turn, a son was born, and he named him Enosh.
At that time people began to invoke the Lord by name.Genesis 4:25-26
Seth is mentioned in the next chapter as well in a similar way.
Adam was one hundred and thirty years old when he begot a son in his likeness, after his image; and he named him Seth.Genesis 5:3
God’s covenant blessing would continue through the descendants of Seth, culminating in Jesus Christ.