The two principal authorities for Apostolic Tradition are Bukhárí († 870 A.D.) and Muslim († 875 A.D.), authors of the collections entitled _Ṣaḥíḥ_. Compilations of a narrower range, embracing only those traditions which bear on the _Sunna_ or custom of the Prophet, are the _Sunan_ of Abú Dáwúd al-Sijistání († 889 A.D.), the _Jámi‘_ of Abú ‘Isá Muḥammad al-Tirmidhí († 892 A.D.), the _Sunan_ of al-Nasá’í († 915 A.D.), and the _Sunan_ of Ibn Mája († 896 A.D.). These, together with the _Ṣaḥíḥs_ of Bukhárí and Muslim, form the Six Canonical Books (_al-kutub al-sitta_), which are held in the highest veneration. Amongst the innumerable works of a similar kind produced in this period it will suffice to mention the _Maṣábíḥu ’l-Sunna_ by al-Baghawí († _circa_ 1120 A.D.). A later adaptation called _Mishkátu ’l-Maṣábíḥ_ has been often printed, and is still extremely popular. [Sidenote: Máwardí († 1058 A.D.).] [Sidenote: Arabic authorities on Ṣúfiism.] [Sidenote: Ghazálí († 1111 A.D.).] Omitting the great manuals of Moslem Jurisprudence, which are without literary interest in the larger sense, we may pause for a moment at the name of al-Máwardí, a Sháfi‘ite lawyer, who wrote a well-known treatise on politics--the _Kitábu ’l-Aḥkám al-Sulṭániyya_, or 'Book of the Principles of Government.' His standpoint is purely theoretical. Thus he lays down that the Caliph should be elected by the body of learned, pious, and orthodox divines, and that the people must leave the administration of the State to the Caliph absolutely, as being its representative. Máwardí lived at Baghdád during the period of Buwayhid ascendancy, a period described by Sir W. Muir in the following words: "The pages of our annalists are now almost entirely occupied with the political events of the day, in the guidance of which the Caliphs had seldom any concern, and which therefore need no mention here."[631] Under the ‘Abbásid dynasty the mystical doctrines of the Ṣúfís were systematised and expounded. Some of the most important Arabic works of reference on Ṣúfiism are the _Qútu ’l-Qulúb_, or 'Food of Hearts,' by Abú Ṭálib al-Makkí († 996 A.D.); the _Kitábu ’l-Ta‘arruf li-Madhhabi ahli ’l-Taṣawwuf_, or 'Book of Enquiry as to the Religion of the Ṣúfís,' by Muḥammad b. Isḥáq al-Kalábádhí († _circa_ 1000 A.D.); the _Ṭabaqátu ’l-Ṣúfiyya_, or 'Classes of the Ṣúfís,' by Abú ‘Abd al-Raḥmán al-Sulamí († 1021 A.D.); the _Ḥilyatu ’l-Awliyá_, or 'Adornment of the Saints,' by Abú Nu‘aym al-Iṣfahání († 1038 A.D.); the _Risálatu ’l-Qushayriyya_, or 'Qushayrite Tract,' by Abu ’l-Qásim al-Qushayrí of Naysábúr († 1074 A.D.); the _Iḥyá’u ‘Ulúm al-Dín_, or 'Revivification of the Religious Sciences,' by Ghazálí († 1111 A.D.); and the _‘Awárifu ’l-Ma‘árif_, or 'Bounties of Knowledge,' by Shihábu ’l-Dín Abú Ḥafṣ ‘Umar al-Suhrawardí († 1234 A.D.)--a list which might easily be extended. In Dogmatic Theology there is none to compare with Abú Ḥámid al-Ghazálí, surnamed 'the Proof of Islam' (_Ḥujjatu ’l-Islám_).