Imam Malik, Imam Ahmad bin Hanbal, most followers of the Shafi’i School and those of the Zahiri consider istishab to be a valid independent source of Shari’ah, Abu Hanifah and the majority of his followers did not consider it an independent source, asserting that just as there should be a textual proof for an issue in the past to be binding, there must be a textual proof for its continuity as well.
Abdul Wahab Khallaf, Masadir al-Tashri’ al-IslamiFima la Nass Fihi, Dar al-Qalam, Kuwait 1414, 6th edition, p.152
