It is reported that ʿUmar b. ʿAbd Al-‘Azīz once wrote to Al-Ḥasan Al-Baṣrī to get a brief exhortation from him, so Al-Ḥasan wrote back , “The dunyā distracts and preoccupies the heart and body, but al-zuhd (asceticism, not giving importance to worldly things) gives rest to the heart and body. Verily, Allāh will ask us about the ḥalāl things we enjoyed, so what about the ḥarām!”
Al-Bayhaqī, Al-Zuhd Al-Kabīr, article 26.