Ibn Abbad of Ronda was one of the early members of the Shadhiliyyah order founded in the Maghrib.  He lived and died in 14th century Morocco.  He left two fairly complete collections of letters (54 letters in all), most of which were written to explain the fundamentals of Sufi spirituality to "individuals who were struggling with specific personal problems."  These letters thus serve as easily-read passages of introduction to many of the Sufi virtues.  Schimmel describes Ibn Abbad as "a quiet friend in whom we can trust, a friend who does not press his ideas on us but rather waits until we come and listen to him and thus slowly understand his deep responsibility for the spritual well being of his readers". In some cases, the letters may even be read as inspirational reading.  Extracted from:

Ibn Abbad of Ronda: Letters on the Sufi Path
translation and introduction by John Renard, S.J.
preface by Annemarie Schimmel
Paulist Press, 1986
238 pgs
ISBN 0-8091-2730-X