Kitāb al-Úzlah by Imām Bustī (317-388 AH).

This is a small booklet, full of light and brimming with wisdom. It is about reclusion as the title suggests. It is written by the noble imām, Ĥāfiž Abū Sulaymān Ĥamad ibn Muĥammad al-Khaţţābī al-Bustī. His biography can be found here.  Imām Bustī was also a lexicologist and a litterateur; his book contains sublime verse.

The contents of the book as described by chapter headings:

1.    Discussion about those who reject reclusion and their proofs.

2.    Concerning that which has been said about reclusion (in the Qur’ān and Sunnah).

3.    Concerning things that help a person in being a recluse and his keeping away from company of those who desire company.

4.    About having a light burden [wealth and belongings] and dependents.

5.    About abstaining from seeking explanations from friends, and of the desirability of meeting them sparingly.

6.    On renouncing that which doesn’t concern oneself, and from indulging from that which is futile.

7.    On being careful of bad companions; and of behaving well with companions and friends.

8.    About the varying dispositions of men.

9.    About the character of the general populace and that, one benefits very little from them.

10.    On being careful of the general public and that one shouldn’t keep suspecting them either; about the fact that one shouldn’t rely on them and abstain from feeling reassured in their company [istināmah].

11.    Lamenting on the decadence of people in our times.

12.    On yearning for death.

13.    About renouncing participation in the affairs of the common people or being trustees to their works, and to remain in the margins [unnoticed].

14.    On the decadence of the elite; and what has been mentioned about wicked scholars and their maladies.

15.    About maladies of the reciters [or scholars/teachers].

16.    About the decadence of leaders; and what has been mentioned in curtailing the company of rulers.

17.    On the necessity of being moderate in either states of reclusion and assembly.