On the day of ‘Arafa, 362 A.H./ 973 CE, the Fatimid Imām-Caliph al-Mu‘izz (d. 975) ordered that a shamsa, a royally commissioned drapery (kiswa) meant to be placed on the Kaaba in Mecca, be showcased in the iwān of his palace at al-Manṣūriya. While named the shamsa, a word meant to denote the brilliant metallic embroideries intended to radiate like a sun, the Fatimid shamsa’s ornamentation was quite different. It consisted of a series of embroidered crescent moons (hilāl) ornamented with luminescent pearls. This textile was meant to be placed on the Kaaba during the Ḥajj, a moment of the calendar year when a large gathering of Muslims from around the world would see it and ponder on the meaning of the Fatimid design and deliberate use of crescent moons as ornamentation. The crescent moon is a frequent occurrence in various cultural facets of the Fatimid ethos, ranging from jurisprudential texts to material culture. This paper argues that a consideration of Fatimid adab literature, particularly panegyric poetry, is necessary to shed light on the meanings of what the hilāl represented in Fatimid society. Specifically, this paper addresses the use of adab literature to understand the Fatimid jurisprudential viewpoint of ruʼyat al-hilāl, the common Muslim practice of sighting the new moon to mark the beginning and ending of the fast in Ramadan. While the Fatimids were considerably pluralistic in their state policies, their implementation of strict regulations against the practice of ruʻyat al-hilāl, which goes against other Islamic legal schools of thought, is noteworthy. Adab is key to understanding this aspect of their policy and its intersection with both jurisprudence and visual culture. Fatimid panegyrics frequently compare the Imām-Caliphs to celestial bodies of spiritual guidance, and in some instances as the embodiment of the crescent moon. These comparisons are more than literary tropes; rather, they echo deep esoteric representations of the cosmos deeply rooted in Ismaili tāʼwīl literature. In this esoteric literature, the Imām-Caliph assumes the role of the master of time (ṣāḥib al-ʿaṣr) and his divine authority and spiritual guidance mirrors the hilāl, since it is a determinant of time according to the Quran. This paper will bring forth several key examples from medieval Fatimid panegyrics and other literary works to weave together a clear understanding of what the hilāl esoterically meant to the Fatimids and its resulting impact on fiqh.