Gen 4:6-8 6 GOD spoke to Cain: "Why this tantrum? Why the sulking? 7 If you do well, won't you be accepted? And if you don't do well, sin is lying in wait for you, ready to pounce; it's out to get you, you've got to master it." 8 Cain had words with his brother. They were out in the field; Cain came at Abel his brother and killed him. Right after God told Cain that he had to master sin he killed Able, so did he master sin?