Bitternes, resentment, and hate all run closely together. Here are some passage to read and meditate on concerning bitterness:

1. The Bible calls us to put away bitterness (Eph 4:31)
2. We’re called to stop biting and devouring one another (Gal 5:15)
3. Bitterness belongs to the sinful nature (Gal 5:19)
4. We’re not to let bitterness take root in the heart (Heb 12:15)
5. Joseph’s brothers allowed bitterness to grow into hatred and murder in their heart (Gen 37)
6. Cain’s anger turned to bitterness, hatred, and murder (Gen 4:3-8)
7. Hatred is forbidden (Lev 19:17)
8. One who hates lives in darkness (1 John 2:9-11)
9. The way of a malicious man is deceitful (Prov 26:24-26)
10. Hatred is murder (1 John 3:11-20, 3:15)

The above list is found in the Quick Scripture Reference for Counseling.