Our Blessed Lord gave Sr. Faustina (for herself only initially) a Novena to His Mercy. She was to start it on Good Friday, that wonderful day when Christ first revealed how merciful and loving He was, by dying for us.
Sr. Faustina wrote in her diary that she began the Novena for the conversion of the whole world that all may recognize God’s Mercy and that all souls may speak of His Goodness.
Jesus said: “I desire the confidence of My people. Let not even the weak and very sinful fear to approach Me, even if their sins be as numerous as all the sands of the earth they will be forgiven in the fathomless pit of My Mercy.”