Purity of the Heart

Once Hasan al-Basri went to Habib al-'Ajami at the time of evening prayers. Hasan heard al-'Ajami mispronounced a word during the prayer. He considered it improper to do his prayers with him, and therefore did them separately. During the night he dreamt the Lord spoke to him: "Hasan, if you had stood behind al-'Ajami and performed your prayers, you would have earned Our Pleasure, and that single prayer of yours would have borne thee greater benefit than all prayers taken together that you have offered in your lifetime. You found fault with his pronunciation but ignored the purity and excellence of his heart. Know it that We cherish a contrite heart much more than the correct pronunciation of words."

... Tadhkirat al-Auliya', Farid al-Din Attar