This Act of Reparation was taught to the three shepherd children to whom Our Lady of Fatima appeared between May 13, 1917, and October 13, 1917. The Act of Reparation was revealed to them by an angel, who taught them to recite the prayer.
Act of Reparation From the Angel of Fatima
Most Holy Trinity, Father, Son and Holy Ghost, adore You profoundly and I offer You the most precious Body, Blood, Soul and Divinity of Jesus Christ, present in all the tabernacles of the world, in reparation for the outrages, sacrileges and indifferences by which He Himself is offended. And by the infinite merits of His Most Sacred Heart and the Immaculate Heart of Mary, I beg of You the conversion of poor sinners.