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….In this hour I will refuse nothing to the soul that makes a request of Me in virtue of My Passion. Our Lord to St Faustina(Diary, 1320)

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 fountain of mercy for us, I trust in you. Our Lord to St Faustina (Diary, 186, 187)