Live with mercy: Do not let your hand be open to receive, but clenched when it is time to give. Ben Sira 4:31
The spiritual gifts give us enlightenment and make us like God, justice is not enough. Although mercy is not one of the most important spiritual gifts in the Old Testament, there are norms in the Sacred Scriptures referring to this spiritual gift: "Be merciful, just as your Father is merciful" Luke 6:36. The Master of Wisdom Ben Sira recommends us to live with mercy (compassion, gentleness, kindness) every day of our lives, mercy opposes the hardness of heart: "Do not let your hand be open to receive, but clenched when it is time to give," Ben Sira 4:31.
Mercy is like a boomerang, when we practice it progressively we bless our neighbor but at the same time we bless ourselves, because with the same rod with which we judge we are judged.
From another point of view, the laws of the universe reward uplifting behaviors that help others and help ourselves: "Do not be deceived: God cannot be mocked. A man reaps what he sows" Galatians 6:7. Many times the turns of life make the little but good that is sown become much and abundant as Jesus explains in the Parable of the Sower, mercy nourishes the soul, gives life, and unites minds and hearts.
In the Bible there are stories of many men who helped angels without knowing it and for that, they received their reward. Like Lot, a man fearful of God, who lived in Sodom and for having given lodging to some angels in his house he was helped, and he was saved with his family from the destruction of the city (Genesis 19:1-29).
Another example in the Old Testament of how mercy works are the miracles of Elisha, with supernatural acts the prophet manifests the perfect mercy of God. Elisha resurrects the son of a Shunammite (2 Kings 4:32-37), multiplies the oil (2 Kings 4:1-7), and the loaves (2 Kings 4:42-44). All these miracles constitute an antecedent of the mercy of Jesus, who performs similar miracles. Jesus in his teachings explains to us that ultimately whoever lives mercy has already complied with all the law.