The phase is based on one of most important prayers in the tradition of our bothers and sisters Eastern Orthodox prayers known as the Jesus Prayer "Jesus Christ, Son of God, have mercy upon me a sinner." Often repeated over many times as a prayer of meditation similar to the Lord's prayer and Hail Mary in Western tradition. It reminds me of when Solomon dedicates the temple to the LORD and people sing out in 2 Chronicles 5-7 “For He is good, For His mercy endures forever." The glory of God falls and out of his mercy it does not consume them. The promise of mercy is given in 2 Chronicles 7:12-18
[SUP]12 [/SUP]Then the Lord appeared to Solomon by night, and said to him: “I have heard your prayer, and have chosen this place for Myself as a house of sacrifice. [SUP]13 [/SUP]When I shut up heaven and there is no rain, or command the locusts to devour the land, or send pestilence among My people, [SUP]14 [/SUP]if My people who are called by My name will humble themselves, and pray and seek My face, and turn from their wicked ways, then I will hear from heaven, and will forgive their sin and heal their land. [SUP]15 [/SUP]Now My eyes will be open and My ears attentive to prayer made in this place. [SUP]16 [/SUP]For now I have chosen and sanctified this house, that My name may be there forever; and My eyes and My heart will be there perpetually. [SUP]17 [/SUP]As for you, if you walk before Me as your father David walked, and do according to all that I have commanded you, and if you keep My statutes and My judgments, [SUP]18 [/SUP]then I will establish the throne of your kingdom, as I covenanted with David your father, saying, ‘You shall not fail to have a man as ruler in Israel.’
We also see the save phrase as a Meditation in Psalm of 106 and 107. Also, who can forget about all those who called out to Christ the Son of David to have mercy on them. So Kyrie, eleison upon us and Let us fight to see his mercy on this generation as well. Amen.