We are called to show mercy because mercy has first been shown to us
“Should not you have had mercy on your fellow servant, as I had mercy on you?” So also my heavenly Father will do to every one of you, if you do not forgive your brother from your heart. Mercy is not only an action of the Father, it becomes a criterion for ascertaining who his true children are. We are called to show mercy because mercy has first been shown to us.
~ Pope Francis