Abu Ali ibn al-Banna

Wikipedia, citing Makdisi (1956a) states the following about al-Banna's diary

Ibn al-Banna kept a diary, of which only part survives. The part that survives is part of the original manuscript itself, written in Ibn al-Banna's own messy handwriting.¹ The language used is a streamlined version of Arabic suitable for quickly taking notes. The diary is valuable as a primary source about 11th-century Baghdad, particularly for events involving the Hanbali community.

The diary's extant part covers a period of just over one year, from 3 August 1068 to 4 September 1069. When Ibn al-Banna began keeping a diary is not known, but he most likely kept writing in it until his death in 1079. The part that survives today eventually ended up in the possession of Diya ad-Din al-Maqdisi, a hadith scholar who had studied under Ibn al-Jawzi. Al-Maqdisi is known to have travelled to Baghdad shortly before Ibn al-Jawzi's death in 1201, and it may have been during this trip that he obtained the present fragment of Ibn al-Banna's diary. In any case, al-Maqdisi later endowed the diary fragment as waqf property for the library of the Diya'iya madrasa he founded in Damascus – a note written in the margin of the first page identifies it as property of the madrasa.

At least two later writers used the diary as a source: Ibn al-Jawzi and Ibn Rajab. Ibn al-Jawzi appears to have had access to parts of the diary that are now lost, but not the current fragment, so it seems that the diary had become separated into multiple parts by then. On the other hand, Ibn Rajab had access to the currently-known part of the diary, but not any others, so the part that survives today was probably in its present state by his time (i.e. none of it has been lost since then).

Ibn al-Banna's diary was meant for his own personal use and was never meant to be published. As evidence of its private nature, it documents the internal dissension within the Hanbali community that he would not have wanted to reveal to the general public (particularly the controversial case surrounding Ibn Aqil), and it also contains unflattering information about Sharif Abu Ja'far, who Ibn al-Banna held in extremely high regard. Most likely, Ibn al-Banna used the diary as a personal notebook for writing down anything he thought was important or interesting, and then later selectively draw upon those notes for material he did intend to publish. Its private nature makes the diary a more reliable source for the events it covers and also "reveals the temperament of the author, his personality, his prejudices, more vividly and more accurately than the stereotyped accounts given in the biographical devoted to him."

Footnotes

1 George Makdisi, who translated the diary into English, described the handwriting this way: "There is a minimum of diacritical marks. The letters themselves are not always clearly traced out; they often appear attached to each other where they should not be, and in many cases, they do not even appear. I spent a great amount of time merely on the deciphering of the text."

Wikipedia, citing Makdisi (1956a:23) states the following about al-Banna's diary

Date. - The problem of dating the Diary is a simple one. The beginning of each lunar month, almost without exception, is established by the author as being such and such a day, even though he did not have anything to report for that particular first day of the month. The result is that, along with other dates given with precision in the text of the Diary, almost every entry which it contains may be likewise dated with precision. Thus the present fragment of the Diary begins on Sunday the first day of the year 461, which corresponds to 3 Aug 1068 of the Christian Era. The last entry is dated the 14th of Dhu'l-Qa'da, 461, corresponding to 4 September 1069.

There are some mistakes in the dates as set down by the author; some he corrected, and others apparently escaped his attention. The dated entries, indicating the date on which the event took place, do not necessarily indicate the date on which the entry was recorded; the author rarely declares having written the report of a given event on the same day of it's occurrence. The month with the lowest amount of entries is Shauwal, 461, where there are only a few lines; while Rabi II, of the same year, is the most documented one. The most frequent and persistent documentation occurs with regard to the case of Ibn 'Aqil.