“Write that when they say this chaplet in the presence of the dying,
I will stand between My Father and the dying person, not as the just
Judge but as the merciful Savior.”Our Lord's words to St. Faustina, Diary 1541
The Origin of the Chaplet of Divine Mercy, from St. Faustina's diary.
St. Faustina with actual diary page superimposed. In passage 474 we learn the origin of the Divine Mercy Chaplet.
(474) In the evening, when I was in my cell, I saw an Angel, the executor of divine wrath. He was clothed in a dazzling robe, his face gloriously bright, a cloud beneath his feet. From the cloud, bolts of thunder and flashes of lightning were springing into his hands; and from his hand they were going forth, and only then were they striking the earth. When I saw this sign of divine wrath which was about to strike the earth, and in particular a certain place, which for good reasons I cannot name, I began to implore the Angel to hold off for a few moments, and the world would do penance. But my plea was a mere nothing in the face of the divine anger. Just then I saw the Most Holy Trinity. The greatness of Its majesty pierced me deeply, and I did not dare to repeat my entreaties. At that very moment I felt in my soul the power of Jesus’ grace, which dwells in my soul. When I became conscious of this grace, I was instantly snatched up before the Throne of God. Oh, how great is our Lord and God and how incomprehensible His holiness! I will make no attempt to describe this greatness, because before long we shall all see Him as He is. I found myself pleading with God for the world with words heard interiorly. As I was praying in this manner, I saw the Angel’s helplessness: he could not carry out the just punishment which was rightly due for sins. Never before had I prayed with such inner power as I did then.
(475) The words with which I entreated God are these: Eternal Father, I offer You the Body and Blood, Soul and Divinity of Your dearly beloved Son, Our Lord Jesus Christ for our sins and those of the whole world; for the sake of His sorrowful Passion, have mercy on us.
(476) The next morning, when I entered chapel, I heard these words interiorly: Every time you enter the chapel, immediately recite the prayer which I taught you yesterday. When I had said the prayer, in my soul I heard these words: This prayer will serve to appease My wrath. You will recite it for nine days, on the beads of the rosary, in the following manner: First of all, you will say one OUR FATHER and HAIL MARY and the I BELIEVE IN GOD. Then on the OUR FATHER beads you will say the following words: "Eternal Father, I offer You the Body and Blood, Soul and Divinity of Your dearly beloved Son, Our Lord Jesus Christ, in atonement for our sins and those of the whole world." On the HAIL MARY beads you will say the following words: "For the sake of His sorrowful Passion have mercy on us and on the whole world." In conclusion, three times you will recite these words: "Holy God, Holy Mighty One, Holy Immortal One, have mercy on us and on the whole world."
The promises to those who recite the Chaplet, from St. Faustina's diary.
Reciting the Chaplet at a Mother of Mercy Messengers presentation at Ave Maria University, Naples,FL.
(687) "Say unceasingly the chaplet that I have taught you. Whoever will recite it will receive great mercy at the hour of death. Priests will recommend it to sinners as their last hope of salvation. Even if there were a sinner most hardened, if he were to recite this chaplet only once, he would receive grace from My infinite mercy. I desire that the whole world know My infinite mercy. I desire to grant unimaginable graces to those souls who trust in My Mercy."
(1565) When I entered the chapel for a moment, the Lord said to me, "My daughter, help Me to save a certain dying sinner. Say the chaplet that I have taught you for him". When I began to say the chaplet, I saw the man dying in the midst of terrible torment and struggle. His Guardian Angel was defending him, but he was, as it were, powerless against the enormity of the soul’s misery. A multitude of devils was waiting for the soul. But while I was saying the chaplet, I saw Jesus just as He is depicted in the image. The rays which issued from Jesus’ heart enveloped the sick man, and the powers of darkness fled in panic. The sick man peacefully breathed his last. When I came to myself, I understood how very important the chaplet was for the dying. It appeases the anger of God.
(1541) “My daughter, encourage souls to say the chaplet which I have given to you. It pleases Me to grant everything they ask of Me by saying the chaplet. When hardened sinners say it, I will fill their souls with peace, and the hour of their death will be a happy one.
Write this for the benefit of distressed souls; when a soul sees and realizes the gravity of its sins, when the whole abyss of the misery into which it immersed itself is displayed before its eyes, let it not despair, but with trust let it throw itself into the arms of My mercy, as a child into the arms of its beloved mother. These souls have a right of priority to My compassionate Heart, they have first access to My mercy. Tell them that no soul that has called upon My mercy has been disappointed or brought to shame. I delight particularly in a soul which has placed its trust in My goodness.
Write that when they say this chaplet in the presence of the dying, I will stand between My Father and the dying person, not as the just Judge but as the merciful Savior."
http://www.mercyimages.com/devotion_chaplet.aspx