The hour of the Lord Jesus’ death, 3pm, is a privileged time as regards the devotion to the Divine Mercy. At that hour, in spirit we stand beneath Christ’s cross in order to entreat for mercy for us and the whole world for the sake of the merits of His passion.
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” (Diary 1320).
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. (Diary 1572)
Immediately, it needs to be explained that what is meant here is not sixty minutes but the moment of Jesus’ agony on the cross, therefore – the 3 o clock prayer.
It is frequently written and said that the Chaplet to the Divine Mercy must be said at 3 pm and that the Chaplet said at that time has a special power. It is thought so due to lack of knowledge of the devotion to the Divine Mercy in the forms conveyed by Sister Faustina and maybe due to the need for a ready-made wording of the prayer.
The prayer at the Hour of Mercy is a separate form of devotion to the Divine Mercy. Jesus associated a specific promise with it and He also said how it should be said. He never mentioned that the Chaplet to the Divine Mercy should be said at that hour.
Reccommended 3 o clock prayer at the Hour of Mercy
“O Blood and Water, which gushed forth from the Heart of Jesus as a fount of Mercy for us, I trust in You.” (Diary 187)
You expired, Jesus, but the source of life gushed forth for souls, and the ocean of mercy opened up for the whole world. O Fount of Life, unfathomable Divine Mercy, envelop the whole world and empty Yourself out upon us. (Diary 1319)
Certainly, at 3pm we can say the Chaplet, as at any other hour during the day and night, however then we do not say the prayer at the Hour of Mercy (but we say the Chaplet).
The Chaplet to the Divine Mercy cannot be the prayer at the Hour of Mercy because it is directed to God the Father (Eternal father, I offer you…), and the prayer at the Hour of Mercy is to be addressed to Jesus directly.
The prayer at the Hour of Mercy when said regularly makes us start having a personal, direct contact with Jesus because it tells us to: meditate upon His Mercy revealed in the Passion, address to Him in a direct manner, like to a very close person, and, it tells us, for the sake of the merits of His Passion, to entreat Him for the graces necessary for us and the world.
* Bold phrases that have at the end the brackets (…) the number, are the messages of Jesus to the holy Sister Faustina Kowalska.
Source: from www.faustyna.pl. The Congregation of the Sisters of Our Lady of Mercy