Among the preserved rasāʼil (letters) of ʿAbd al-Ḥamīd al-Kātib (d. 132/ 750), the testament written for the ʿAbdallāh, the son of the last Umayyad caliph, Marwān II (r. 127-132/745–750), serves as one of the most pivotal legal-political treatises for early Islamic legal history. ʿAbd al-Ḥamīd al-Kātib was the head of the chancery under Marwān II (r. 127-132/745–750). He elucidated in this testament matters of statecraft, particularly the duties and functions of the ṣāḥib al-shurṭa, the head of the elite military corps. In this treatise, ʿAbd al-Ḥamīd describes the ṣāḥib al-shurṭa as an official who acted as both an elite military commander and magistrate responsible for investigating criminal cases and punishing them in accordance with the judgments of the ruler.
The source was edited (along with other letters) by the late Iḥsān ʻAbbās in his book, ʿAbd al-Ḥamīd b. Yaḥyá al-Kātib, wa-mā Tabaqqá min rasāʼilih wa-rasāʼil Sālim Abī Al-ʻAlāʼ. Amman, Jordan: Dār al-Sharq, 1988, and scans of the few pages dedicated to the shurṭa have been made available.