Muhammad b. Musa b. al-Mutawakkil رضي الله عنه narrated to us. He said: Sa`d b. `Abdullah narrated to us. He said: Al-Qasim b. Muhammad al-Isfahani narrated to us from Sulayman b. Dawud al-Munqari from Hafs b. Ghiyath al-Nakha`i al-Qadi. He said: I said to al-Sadiq Ja`far b. Muhammad عليه السلام: What is asceticism in this world? So, he said: Allah has defined that in His Book. He says, “So that you may not grieve at the things you fail to get, nor rejoice over that which has been given to you.” (57:23)