I would just like to give you an example to illustrate my point, which should hopefully be sufficient: Imam Muhammad Ibn Hasan as-Shaybani was asked that why have you not written a book in asceticism (Tasawuf/Zuhad)? He replied: ' have I not written the Book of Trade and Commerce!!!' (Kitab al-Boyoou') (Hasheaya of Hidaya by Imam Laknawi, Kitab ar-ribaa)