A second revised edition of a text attributed to Muhammad ibn ‘Isa al-Tirmidhi (d. 279/892) and called Bayan al-Farq bayn al-Sadr wal-Qalb wal-Fu’ad wal-Lubb, edited with a brief introduction by Yousef Meri is now available from the Royal Islamic Strategic Studies Centre in Amman, Jordan (ISBN: 978-9957-8533-5-8). A pdf may be downloaded from the RISSC website by clicking here.