I believe you’re referring to
The Divine Mercy Chaplet which is a powerful prayer and can be prayed at any time and for any intention. The significance of praying the Chaplet at the “Hour of Great Mercy” – the 3 pm hour-- is that Jesus attaches a specific promise to it:
Jesus to St. Faustina:
“
At three o’clock, implore My mercy, especially for sinners; and if only for a brief moment, immerse yourself in My Passion, particularly in My abandonment at the moment of agony. This is the hour of great mercy for the whole word. I will allow you to enter into My mortal sorrow. In this hour, I will refuse nothing to the soul that makes a request of Me in virtue of My Passion…” (1320)
And again here:
“
I remind you, My daughter, that as often as you hear the clock strike the third hour, immerse yourself completely in My mercy, adoring and glorifying it; invoke its omnipotence for the whole world, and particularly for poor sinners; for at that moment mercy was opened wide for every soul. In this hour you can obtain everything for yourself and for others for the asking it was the hour of grace for the whole world – mercy triumphed over justice.**” (1572)
So how do we go about doing so? One way of course is by praying the Chaplet, directing our intentions to Jesus in virtue of His passion. In cases where circumstances do not permit this, Jesus says,
“
My daughter, try your best to make the Stations of the Cross in this hour, provided that your duties permit it; and if you are not able to make the Stations of the Cross, then at least step into the chapel for a moment and adore, in the Blessed Sacrament, My Heart, which is full of mercy; and should you be unable to step into the chapel, immerse yourself in prayer there where you happen to be, if only for a very brief instant. I claim veneration for My mercy from every creature, but above all from you, since it is to you that I have given the most profound understanding of this mystery.” (1572)
A “brief prayer” could be a short, exclamatory prayer (3x) such as:
“O Blood and Water which gushed forth from the Heart of Jesus as a Fount of Mercy for us, I trust in you!” (309)
“Jesus, for the sake of Your sorrowful Passion, have mercy on us!”
“Most Merciful Heart of Jesus, protect us from the just anger of God.” (1526)
“O Jesus, have mercy! Embrace the whole world and press me to Your Heart … O Lord, let my soul repose in the sea of Your unfathomable mercy.” (869)
To answer your question, yes the Chaplet really does work. Once when I was greatly suffering, I waited for the 3 pm hour to strike to pray the Chaplet. As soon as I hit the last bead, I was instantly relieved.
Here are some testimonies on the website for
The Centre for Divine Mercy
God Bless,
Josie