Imam Ahmad Zarruq (رحمة الله عليه), the 15th century Maliki scholar and Muhaddith, commenting on the indispensability of both Tasawwuf (Sufism) and the Shariah:
“So there is no Tasawwuf except through comprehension of Sacred Law or Shari’a, for the outward rules of Allah ta’ala are not known save through it, and there is no comprehension of Sacred Law or Shari’a without Tasawwuf, for works are nothing without the sincerity of approach, as expressed by the words of Imam Malik (رحمة الله عليه):
‘He who practices Tasawwuf without learning Fiqh corrupts his faith, while he who learns Fiqh without practicing Tasawwuf corrupts himself. Only he who combines the two proves true.'”
(Iqaz al-himam fi sharh al-Hikam, Ibn ‘Ajiba, Ahmad ibn Muhammad, and Ahmad ibn Muhammad Ibn ‘Ataillah, Mustafa al-Babi al-Halabi wa Awladuhu, Cairo, 1972, pp. 5-6).