When was the last time you used the word "mercy" or "merciful"? Does that suggest it's a concept that has gone out of fashion? We think more in terms of what is "fair" perhaps today.
But the bible sees this concept as crucial to our dealings with God and other people.
We need God to treat us with mercy because we so often make a mess of things. If he treated us only with justice we'd all deserve condemnation.
Because we all mess up we need mercy to be the oil that lubricates our human relationships also.
Here are some bible verses on which to reflect....

Mercy

• Hesed = covenant-love; loving-kindness (400 times in OT)
• “The steady persistent refusal of God to wash his hands of wayward Israel” (Snaith)
• Charis = grace; Eleos = mercy (78 times in NT)
• “Grace is concerned for man, as guilty; mercy, as he is miserable” (Trench)
• “Have mercy on me, O Lord” (Psalm 86v3)
• God is “the Father of mercies” (2Cor 1v3; Ex 34v6; Ps 86v15, etc)
• We are saved because of his mercy (Titus 3v5)
• Jesus was often “moved with compassion” (Mat 9v36)

Be merciful

• And what does the LORD require of you? To act justly and to love mercy and to walk humbly with your God. (Micah 6v8)
• “Go and learn what this means: ‘I desire mercy, not sacrifice.’ For I have not come to call the righteous, but sinners.” (Mat 9v13, quoting Hosea 6v6)
• “Be merciful as your Father also is merciful” (Luke 6v36)
• “The merciful will receive mercy” (Mat 5v7)
• “Judgment without mercy will be shown to anyone who has not been merciful. Mercy triumphs over judgment!” James 2v13)
• Christians are to “put on heartfelt compassion” (Col 3v12)