2 Samuel 19:23, 29, 33 Therefore the king said unto Shimei, thou shalt not die. And the king sware unto him….And the king said unto him (Mephibosheth), Why speakest any more of thy matters? I have said, Thou and Ziba divide the land….And the king said to Barzillai, Come thou over with me, and I will feed thee with me in Jerusalem.
The one who is in power may have the authority to either judge and execute or to show mercy and set free. When David came back to Jerusalem and was restored to power, he decided to exercise that power by being merciful. Justice is required in a sovereign, but mercy is a choice.
David chose not to execute Shimei, who had earlier cursed David. Now David had the opportunity to execute judgment for his crime, but he let him go and set him free. Mephibosheth was a potential enemy, being of the house of Saul, but David decided to be merciful and show kindness and invite him to his table. Barzillai had supported David and supplied him during his flight from Absalom, and David did not forget his kindness and repaid him with mercy by inviting the old and weakened man to his palace.
Our Almighty God is the one with supreme authority and power over us. He can justly judge and condemn us to eternal separation from life, but in love He has chosen to show mercy and give life to those who have offended Him and sinned against God. “God so loved….” We have within us the life of God which holds and dispenses the power of God to give mercy and forgiveness.