Blessed are the merciful,
for they will be shown mercy.
We often think of 'mercy' as forgiveness. However, when Jesus taught about forgiveness (e.g. in connection with the Lords' prayer) He used a different Greek word (aphiemi - Matt 6:12). 'Mercy' (Greek eleemon) in the Gospels can mean forgiveness, but more often it means an action of deliverance in the sense of healing or giving. For example, when a blind or crippled person cried out to Him "Lord, have mercy" they weren't asking for forgiveness - they were asking to be delivered from their affliction. So, in Matt 6:2 a related word eleemosune means giving alms to the poor.
According to Jesus, "justice, mercy and faith" were the weightier matters of the Law which were neglected by the religious leaders (Matt 23:23). On two occasions Jesus quoted Hosea 6:6 "I desire mercy and not sacrifice" (Matt 9:13; 12:7). In other words,
"what God demands is not so much activity directed Godward but
lovingkindness benefitting other people".*
* Glen H. Stassen and David P. Gushee, Kingdom Ethics, Intervarsity Press, 2003, p. 44