Sufyaan ath-Thawree used to spend the nights and the days crying and the people used to ask him, "Why do you cry, is it due to the fear of Allh? He said, "No." They said, "Is it due to the fear of the Hellfire?" He said, "No. It is not the fear of Hellfire that makes me cry, what makes me cry is that I have been worshipping Allh all these years and doing scholarly teaching, and I am not certain that my intentions are purely for Allah."