At his first praying of the Angelus and address, the Holy Father told the crowd of 300K this experience.
The Pope “told a story, of an elderly widow he encountered during a Mass for the sick celebrated in connection with a visit of the image of Our Lady of Fatima. “I went to confession during the Mass,” he said, “and near the end – I had to go to do confirmations afterward, and an elderly lady approached me – humble [she was] so very humble, more than eighty years old. I looked at her, and said, ‘Grandmother,’ – where I come from, we call elderly people grandmother and grandfather – ‘would you like to make your confession?’ ‘Yes,’ she said – and I said, ‘but, if you have not sinned…’ and she said, ‘we all have sinned.’ [I replied], ‘if perhaps He should not forgive [you]?’ and, sure, she replied, ‘The Lord forgives everything.’ I asked, ‘How do you know this for sure, madam?’ and she replied, ‘If the Lord hadn’t forgiven all, then the world wouldn’t [still] be here.’ And, I wanted to ask her, ‘Madam, did you study at the Gregorian (the Pontifical Gregorian University, founded in 1551 by St Ignatius Loyola, the oldest Jesuit university in the world)?’ – because that is wisdom, which the Holy Spirit gives – interior wisdom regarding the mercy of God. Let us not forget this word: God never tires of forgiving us,” he repeated, “but we sometimes tire of asking Him to forgive us.” Pope Francis went on to say, “Let us never tire of asking God’s forgiveness.”
Source: Vatican Radio