Mercy Unto Thousands refers to the title of a biography of Mother Mary Catherine McAuley, founder of the Sisters of Mercy, as well as a biblical quote often associated with the theme of God's mercy and loving-kindness, such as Exodus 20:6 and Deuteronomy 5:10. This phrase describes the abundant divine grace for those who love and obey His commandments, and is often used in religious contexts and biographies of spiritual figures.