Nursi on the Mahdi

The future events that Most Noble Messenger (Upon whom be blessings and peace) predicted were not isolated incidents; he rather predicted general and recurring events in a particular way. Those events, however, had many sides to them and each time he mentioned them, he explained a different side. Then the narrator of the Hadiths combined all of those sides and they sometimes appear contrary to reality. There are, for example, varying narrations concerning the Mahdi, each with different details and descriptions. However, as was explained in a section of the Twenty-Four Word, the Noble Messenger (Upon whom be blessings and peace) gave the tidings, relying on revelation, of a Mahdi who would come in every century to preserve the morale of the believers, help them not to fall into despair in the face of disasters, and link the hearts of the believers with the people of the Prophet's Family, who constitute a luminous line in the world of Islam.  Every century has seen a Mahdi from the Prophet's Family, or several, similar to the Great Mahdi who is promised to come at the end of time. One of the 'Abbasid Caliphs even, who were said to be descendants of the Prophet's Family, was a Mahdi who possessed many of the Great Mahdi's characteristics. In this the attributes of the Mahdi's deputies and of the spiritual poles [aqṭāb] who were Mahdis who were to precede the Great Mahdi and were samples and forerunners of him, were confused with the attributes of the Great Mahdi himself, and the narrations concerning him were seen to conflict with one another.

-Fourth Principle, The Miracles of Muhammad - Fourth Sign, Letters 1928-1932 by Said Nursi, translated from the Turkish 'Metrubat by Ṣükran Vahide, (Istanbul: Sözler Publications, 2010), p. 122.