Genesis 4:6-7 (NRSV)
6 The Lord said to Cain, “Why are you angry, and why has your countenance fallen? 7 If you do well, will you not be accepted? And if you do not do well, sin is lurking at the door; its desire is for you, but you must master it.”
1 Peter 5:8-9 (NRSV)
8 Discipline yourselves, keep alert. Like a roaring lion your adversary the devil prowls around, looking for someone to devour. 9 Resist him, steadfast in your faith, for you know that your brothers and sisters in all the world are undergoing the same kinds of suffering.