Although Ibn Hajar al-'Asqalani is primarily known for his seminal scholarship in the field of prophetic traditions or hadith studies, he was also an accomplished poet. In fact, as this paper reveals, one of the poems that Ibn Hajar included in his carefully crafted collection from the ninth/fifteenth century struck a deep chord of Muslim memories surrounding a restored Islamic caliphate. Far from the image of complete apathy to the Cairene Abbasids that has long been conventional wisdom, Ibn Hajar’s panegyric for al-Musta'in (r. 808–16/1406–14) lauded the caliph’s assumption of the sultanate as a restoration of legitimate rule to the blessed family of the Prophet. In crafting his poem, Ibn Hajar draws upon a deep reservoir of devotional love for the Prophet’s family in the late Mamluk era, embodied by al-Musta'in as the descendent of the Prophet’s uncle al-'Abbas, as well as a dynamic and evolving Islamic legal tradition on matters of governance. Even though al-Musta'in’s combined reign as sultan and caliph lasted only a matter of months, Ibn Hajar’s commemoration of it became a famous piece of cultural lore down through the last years of the Mamluk Sultanate and past the Ottoman conquest of Egypt. In addition to exploring the intertwined histories of Ibn Hajar, al-Musta'in, and their contemporaries, this interdisciplinary paper analyzes published and manuscript recensions of Ibn Hajar’s poetry, topographies of Cairo, Mamluk chancery documents, and treatises on Islamic law and hadith literature to elucidate the religious and socio-political complexity of veneration for the Abbasid caliphate in the late Mamluk era.