“Be kind to one another, tenderhearted, forgiving one another, as God in Christ forgave you.” (Eph. 4:32 ESV)

Kindness benefits you

“A man who is kind benefits himself, but a cruel man hurts himself.” (Prov. 11:17 ESV)

Put on compassionate hearts

“Put on then, as God's chosen ones, holy and beloved, compassionate hearts, kindness, humility, meekness, and patience.” (Col. 3:12 ESV)

Therefore…

“But love your enemies, and do good, and lend, expecting nothing in return, and your reward will be great, and you will be sons of the Most High, for he is kind to the ungrateful and the evil.” (Luke 6:35 ESV)

“Finally, all of you, have unity of mind, sympathy, brotherly love, a tender heart, and a humble mind.” (1 Pet. 3:8 ESV)