From an illuminated Ottoman dua kitabi or 'prayer book' by Hasan Rashid (Istanbul, 1845) once the property of a Topkapi harem lady. The sword of Ali, Dhu l-Fiqar or Zulfiqar, is bifurcated and considered exceptionally holy by Shia Muslims. The Arabic term 'du'a' is generally translated into English as 'prayer', though a more exact rendering would be 'supplication'. The term is derived from an Arabic word meaning to 'call out' or to 'summon', and Muslims regard this as a profound act of worship. This is when Muslims connect with God and ask him for forgivness or appeal for his favour. The Prophet Muhammad is reported to have said 'Dua is the very essence of worship', while one of Allah's commands expressed through the Qur'an is for Muslims to call out to Him: 'Call to Me; I will answer your prayers'. There is a special emphasis on du'a in Muslim spirituality and early Muslims took great care to record the supplications of Muhammad and transmit them to subsequent generations. These tradi