Al-Sahifat al-Sajjadiyya is the oldest manual of supplications in Islamic sources, and one of the most seminal works of Islamic spirituality. It was composed in the 8th century AD by the Prophet's great grandson, Ali b. al-Husayn, known as Zayn al-Abidin, who was revered in his own time as an exemplar of piety and as a foremost authority on prophetic traditions and law. He is counted by the Shi'a as the fourth of their Imams, and among them the Sahifa ranks behind the Qur'an and Ali b. Abi Talib's Nahj al-balagha . The present translation is thoroughly annotated and is accompanied by a translation of another work attributed to Zayn al-Abidin, The Treatise on Rights. Together, these texts will contribute significantly to our understanding of Islamic spirituality and of the Muslim's standing in relation to God and the community, not only in the early period, but, given the widespread use of the Sahifa as a devotional guide, up to the present day. Readership: scholars and students of religion and theology, within the Muslim and non-Muslim worlds; and students of the Middle East and the history of ideas.