This is a prayer taught to St. Faustina by Jesus when he appeared to her. We celebrate Jesus appearing to St. Faustina and what he told her on this day. Here is one of the prayers:
Eternal Father, I offer you the Body and the Blood, Soul and Divinity or your dearly beloved Son, Our Lord, Jesus Christ, in atonement for our sins and those of the whole world. Fot the sake of his sorrowful Passion, have mercy on us and on the whole world.
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