The Bible specifically warns against bitterness: “See to it that no one falls short of the grace of God and that no bitter root grows up to cause trouble and defile many.” (Hebrews 12:15)
'But you . . . belong to God; so run from all these evil things, and follow what is right and good. Pursue a godly life, along with faith, love, perseverance, and gentleness.' 1 Timothy 6:11