Ha-Maamar be-Qaddaat ha-dever (Treatise on Pestilential Fever), composed by an anonymous author, is one of several treatises devoted to the subject of plague that exist in Hebrew literature. The treatise is basically a concise regimen of health as it was common throughout the Middle Ages that has been adapted to the special case of the plague and that has been supplemented with a final section of remedies for the time of the plague. Although we do not know the name of the author nor where and when he lived and composed the treatise, we can draw some conclusions from the foreign, non-Hebrew terminology used in the treatise. As several of the foreign terms used for the different plants and remedies are in old Spanish, it seems reasonable to suppose that the author hailed from the Iberian Peninsula and possibly composed the treatise there as well. The frequent quotations in the supplementary section 21 from Spanish Islamic physicians like Ibn Rushd, al-Zahrāwī, al-Ghāfiqī and above all Ibn Zuhr also confirm such a supposition.