In October 1937 in Cracow the Lord Jesus said to Sister 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 world. Such is the history of the origin of this form of worship of the Divine Mercy. A few months later, Jesus repeated His request defining precisely the aim of institiution of this form of cult, how to observe the Hour of Mercy, and mentioning what promises are connected with saying the prayer at this hour. He also defined the conditions which had to be met for prayers at this hour to be heard.

The Hour of Mercy is a form of the cult in which we worship the moment of Christ's agony on the Cross (3 p.m.) when grace became available to the whole world and mercy triumphed over justice. What is meant here by the "hour" is not a clock hour or 60 minutes of prayer, but saying a prayer at the moment when the clock strikes the third hour, that is at the moment of Christ's agony on the Mount of Calvary. This form of worship of the cult of the Divine Mercy can be practiced not only on Good Friday, or on every Friday of the month, but everyday. It is a special time in the devotion to the Divine Mercy.

At this hour the Lord Jesus wants us to meditate even though for a brief moment upon His sorrowful passion in which the mystery of His mercy is revealed in the fullest possible way. Getting to know this mystery leads to prayer of praise and thanksgiving, as well as begging for graces for the whole world, and especially for sinners, for at that moment mercy was opened wide for every soul.

The Lord Jesus attaches the promise of all possible graces to the prayer at this special hour. In this hour, I will refuse nothing to the soul that makes a request of Me in virtue of My Passion. In this hour you can obtain everything for yourself and for others for the asking. At the same time, Jesus pointed out that there were three necessary conditions which had to be met for prayer at this hour to be heard: the prayer should be said at three o'clock in the afternoon, it was to be addressed to Jesus, and it was to refer to the values and merits of His Passion. Moreover, it should be added that the object of the prayer has to be in accordance with the will of God, and that the prayer should be trustful, persevering and combined with the practice of active love of one's neighbor, which is a condition of genuine devotion to the Divine Mercy.

The Lord Jesus also gave Sr. Faustina some detailed advice relating to the ways in which she should pray at the Hour of Mercy: 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, if only for a brief instant.

The Hour of Mercy is currently becoming a time of everyday prayer for the apostles of the Divine Mercy the world over. That is why, as if in a continual act of prayer, the faithful all over the world unite with Jesus dying on the Cross - and fulfilling His request - implore for God's mercy for the world and particularly for sinners.