The Lord said to Blessed Faustina: "You will recite this chaplet on the beads of the Rosary in the following manner:"

First of all, you will say one OUR FATHER, one 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.   (Diary, 476)

Our Lord said to Blessed Faustine:
Unceasingly recite this chaplet that I have taught you. Whoever will recite it will receive great mercy at the hour of death ... Priest will recommend it to sinners as their last hope of salvation. Even the most hardened sinner, if he recites this chaplet even once, will receive grace from My infinite mercy (687) ... Oh, what great graces I will grant to souls who will recite this chaplet (848) ... Through the chaplet you will obtain anything, if what you ask for is compatible with My will (1731) ... I want the whole  world to know My infinite mercy. I want to give unimaginable graces to those who trust in My mercy (687).