However, the classification of madaris as "universities" is disputed on the question of understanding of each institution on its own terms. In madaris, the ijāzahs were only issued in one field, the Islamic religious law of sharīʻah, and in no other field of learning. Other academic subjects, including the natural sciences, philosophy and literary studies, were only treated "ancillary" to the study of the Sharia. For example, a natural science like astronomy was only studied (if at all) to supply religious needs, like the time for prayer. This is why Ptolemaic astronomy was considered adequate, and is still taught in some modern day madaris. The Islamic law undergraduate degree from al-Azhar, the most prestigious madrasa, was traditionally granted without final examinations, but on the basis of the students' attentive attendance to courses. In contrast to the medieval doctorate which was granted by the collective authority of the faculty, the Islamic degree was not granted by the teacher to the pupil based on any formal criteria, but remained a "personal matter, the sole prerogative of the person bestowing it; no one could force him to give one".