Yeah, you might note that’s not what I said.
And you didn’t answer my question.
It IS recommended, but NOT compulsory:
Jesus asked that all who venerate His mercy honour His Passion by remembering Him with this prayer at 3 O’Clock in the afternoon. He asks us, “If only for a brief moment, immerse yourself in My Passion, particularly in My abandonment at the moment of agony”. (Diary 1320) At this moment, He asks us to implore His Mercy, especially for sinners. He told St. Faustina, “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”. (Diary 1572)
The short prayer which Jesus taught St. Faustina for the veneration of His Mercy at 3 O’Clock is, “O Blood and Water, which gushed forth from the Heart of Jesus as a Fount of Mercy for us, I trust in You”. This is also known as the Conversion Prayer. Jesus told St. Faustina, "I desire that you know more profoundly the love that burns in My Heart for souls, and you will understand this when you meditate upon My Passion. Call upon My mercy on behalf of sinners; I desire their salvation. When you say this prayer, with a contrite heart and with faith on behalf of some sinner, I will give him the grace of conversion. This is the prayer: “O Blood and Water, which gushed forth from the Heart of Jesus as a fount of Mercy for us, I trust in You.” (Diary 186-187) St. Faustina also created her own prayer for this moment, which is: 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)
Jesus asked, that as often as we “hear the clock strike the third hour” that we deeply contemplate His Passion, “if only for a brief moment”. But after we observe the moment of the death of the Messiah at 3 O’Clock with this special prayer, we then have before us “the hour of great mercy for the whole world”. (Diary 1320) Jesus has let us know that in Heaven, the 3 O’Clock hour is a special holy hour, as He said, “it was the hour of grace for the whole world — mercy triumphed over justice…In this hour, you can obtain everything for yourself and for others for the asking…In this hour, I will refuse nothing to the soul that makes a request of Me in virtue of My Passion”. (Diary 1320, 1572) He asked St. Faustina, that if she had time she should make the Stations of the Cross during this special hour. He acknowledged that her duties might prevent her from being able to do this, but He asked that on these occasions, she step into a church and adore His Mercy, if only for a brief moment. He also said that if she did not have the opportunity to enter a church, she could pause, wherever she was, and “immerse yourself in prayer there where you happen to be, if only for a very brief instant”. (Diary 1572)