عِدَّةٌ مِنْ أَصْحَابِنَا عَنْ سَهْلِ بْنِ زِيَادٍ عَنْ يَحْيَى بْنِ الْمُبَارَكِ عَنْ عَبْدِ اللَّهِ بْنِ جَبَلَةَ عَنْ إِسْحَاقَ بْنِ عَمَّارٍ عَنْ أَبِي عَبْدِ اللَّهِ ( عليه السلام ) قَالَ قُلْتُ جُعِلْتُ فِدَاكَ رُبَّمَا كَثُرَ الشَّعْرُ فِي قَفَايَ فَيَغُمُّنِي غَمّاً شَدِيداً فَقَالَ لِي يَا إِسْحَاقُ أَ مَا عَلِمْتَ أَنَّ حَلْقَ الْقَفَا يَذْهَبُ بِالْغَمِّ .
8. A number of our people have narrated from Sahl ibn Ziyad from Yahya ibn al-Mubarak from ‘Abd Allah ibn Jabalah from Ishaq ibn ‘Ammar who has said the following: “I once said to abu ‘Abd Allah (a.s.), ‘I pray to Allah to keep my soul in service for your cause, at times hairs grow at my back and it causes great worries for me.’ He (the Imam) said to me, ‘O Ishaq did you not know that shaving one’s back dispels anxieties?”’