Genesis 4:3-5, 15, 25

And in the course of time Cain brought to the LORD an offering of the fruit of the ground. But Abel brought [an offering of] the [finest] firstborn of his flock and the fat portions. And the LORD had respect (regard) for Abel and for his offering; [Heb 11:4] but for Cain and his offering He had no respect. So Cain became extremely angry (indignant), and he looked annoyed and hostile.

And the LORD said to him, “Therefore, whoever kills Cain, a sevenfold vengeance [that is, punishment seven times worse] shall be taken on him [by Me].” And the LORD set a [protective] mark (sign) on Cain, so that no one who found (met) him would kill him. [Gen 4:24]

Adam knew [Eve as] his wife again; and she gave birth to a son, and named him Seth, for [she said], “God has granted another child for me in place of Abel, because Cain killed him.”