“A deed is not accepted unless it is sincere and correct: sincere, done for Allah alone, and correct, in accordance with the Sunnah.”

Al-Fudayl ibn ‘Iyad (d. 187 AH) said this explaining the Qur’anic phrase “the best in deed” in Surat al-Mulk, and Ibn Kathir preserves it in his commentary on that verse. The two conditions are not interchangeable, as he goes on to say: a deed that is sincere but wrong is not accepted, and a deed that is correct but insincere is not accepted either.