Today's Scripture reading is Matthew 5:43-45.
Verse 44, "...and pray for them which despitefully use you,"
This portion of the Sermon on the Mount goes completely against our human nature.  It is not natural to love our enemies and for sure it is not natural to pray for someone who slanders or insults us.  Please keep in mind, the Lord Jesus is not asking us to do something that is natural.  If we are commanded to pray for those who despitefully use us then our Heavenly Father will enable us to do so.  How often do we apply the enabling God has for us?  How often do we return the despitefully use instead of praying?  It is definitely a challenge that can be overcome as we yield to the Holy Spirit and say NO to the flesh.  Our fleshly response will tend to be revenge.  This is clearly not taught in the Word of God.  God said He would do the repaying in Romans 12:19.  I close with a song from many years ago, "You can talk me...all that you please...you can talk about me....all that you please...you can talk about me all that you please, I'll talk about you down on my knees...all my sins are washed away, praise the Lord!"