Three o’clock in the afternoon or 15 hours is the hour of the death of Our Lord Jesus Christ on the Cross, it is the hour in which he finally paid the debt of our sins.
Being He the innocent lamb is sacrificed for us the sinners and guilty.
It is also the greatest act of Love since he gave his life not only for his friends but for his enemies.
And finally the supreme act of mercy, his infinite mercy. Well, as he said of the souls in purgatory: my mercy does not want it but my justice demands it, and being also infinitely just and to satisfy it He himself paid the infinite debt of all of us.
The 3 o’clock prayer
Jesus himself asked Sister Faustina that the time of her death was at 3 in the afternoon. In this hour we try to remain in spirit at the foot of the Cross of Christ, in order to beg for mercy for oneself and for the whole world by virtue of the merits of her Passion. About this hour of Mercy, the Lord said to Sister Faustina: At three o’clock, pray for My mercy, especially for sinners and even if only for a very brief moment, immerse yourself in My Passion, especially in My abandonment at the moment of My agony. This is the hour of great mercy for the whole world (Diary 1320). It should be clarified here, that it is not an exact hour of the clock (60 minutes), but rather it is about keeping in mind the moment of Jesus’ agony on the cross, that is, accompanying him by praying at three in the afternoon.
Jesus does not propose a specific prayer for this time of 3 in the afternoon; Rather, he said that one could, for example, pray the Via Crucis, visit the Blessed Sacrament, and if time does not allow it due to obligations, at least for a few moments, wherever we are, we must try to unite with Him when he is dying on the Cross, if only for a brief moment. The object of this prayer is the mystery of the Passion of Christ. This prayer in the Hour of Mercy must meet certain conditions: it must take place at three in the afternoon (when the clock shows the exact time), it must be addressed directly to Jesus, and in our supplications and petitions, we must refer to the merits and value of his painful Passion.
Because normally one is in multiple occupations in the application, an alarm can be activated that alerts us just when it is 3 in the afternoon or 15 hours, along with an ejaculation to be able to stop at least a moment to accompany Jesus on the cross .