If you need mercy, show mercy, and you shall receive it, for that is what Jesus taught in the Sermon on the Mount,

“Blessed are the merciful, for they shall obtain mercy” (Matthew 5.7).

Think of it this way. To whom would you show mercy? Would it not be the person who is merciful, whereas, you would resist showing it to the cruel? Therefore, realize that God also shows mercy to the merciful, and that man shows mercy to the merciful.