Jesus asked Saint Faustina, and through her us, to celebrate this Hour of Great Mercy, promising tremendous graces to those who would, both for themselves and on behalf of others.
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 … In this hour I will refuse nothing to the soul that makes a request of Me in virtue of My Passion. (Diary 1320).
As often as you hear the clock strike the third hour immerse yourself completely in My mercy, adoring and glorifying it, invoke it’s 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.
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 Most Blessed Sacrament. My Heart, which is full of mercy: and should you be unable to step into chapel. immerse yourself in prayer there where you happen to be, if only for a very brief instant. (Diary 1572)