Jesus speaks to St. Faustina on The Merits of Meditating on His Passion

St. Faustina writes in her Diary - Passage 369
Before the eight-day retreat, I went to my spiritual director and asked him for certain mortifications for the time of the retreat. However, I did not receive permission for everything I asked for, but for some things only. I received permission for one hour of meditation on the Passion of the Lord Jesus and for a certain humiliation. But I was a little dissatisfied at not receiving permission for everything I had asked. When we returned home, I dropped into the chapel for a moment, and then I heard this voice in my soul:  "There is more merit to one hour of meditation on My sorrowful Passion than there is to a whole year of flagellation that draws blood; the contemplation of My painful wounds is of great profit to you, and it brings Me great joy. I am surprised that you still have not completely renounced your self-will, but I rejoice exceedingly that this change will be accomplished during the retreat."