Exodus 34:6-7, Psalm 51:1, Matthew 5:7
The Richest Word
The Hebrew word hesed — often translated "steadfast love," "mercy," "lovingkindness," or "covenant faithfulness" — is one of the richest words in the entire Old Testament. It appears over two hundred and fifty times and is used almost exclusively of God.
Hesed describes the loyal, committed, covenant-faithful love that God shows to His people — a love that goes beyond what is strictly required, that persists in the face of failure, that is not earned and cannot be forfeited by anything short of final, wilful rejection.
When Moses asked to see God's glory, God proclaimed His name: "The Lord, the Lord, a God merciful and gracious, slow to anger, and abounding in steadfast love and faithfulness, keeping steadfast love for thousands, forgiving iniquity and transgression and sin." (Exodus 34:6-7). This self-disclosure is quoted or echoed more than any other passage in the Old Testament — it is Israel's foundational understanding of who God is.
Mercy vs. Grace
These two attributes are closely related but distinct:
Grace is giving good that is not deserved — blessing the unworthy with gifts they could never merit.
Mercy is withholding the punishment that is deserved — compassion toward the miserable that relieves their distress rather than exacting what justice requires.
Both are expressions of God's love; both are demonstrated supremely at the cross.
Mercy in Practice
The Psalms are saturated with appeals to God's mercy — "Have mercy on me, O God, according to your steadfast love." (Psalm 51:1) — and with celebration of it: "His mercy is great above the heavens." (Psalm 108:4). The people of God know themselves to be receivers of undeserved mercy, and this shapes both their prayer and their praise.
Jesus' parable of the Pharisee and the tax collector (Luke 18:9-14) places the appeal to mercy at the centre of genuine prayer. The Pharisee catalogues his credentials; the tax collector can only say "God, be merciful to me, a sinner!" Jesus' verdict: the tax collector, not the Pharisee, went home justified.
The Demand Mercy Makes
Those who have received mercy are required to show it. The Sermon on the Mount: "Blessed are the merciful, for they shall receive mercy." (Matthew 5:7). The parable of the unforgiving servant (Matthew 18:21-35) is a severe warning: the person who has received immeasurable mercy and refuses to show it to others has not understood the mercy they received.