Al-Ishnani quotes his grandfather quoting Muhammed ibn `Ammar quoting Masa ibn Isma`il quoting Hammad ibn Salamah quoting Aba al-Tufayl quoting Ali ibn Abi Talib (A.S.) saying that the Messenger of Allah (A.S.) said to him, “O Ali (A.S.)! There is a treasure for you in Paradise, and you are Thul-Qarnain (Double-horns) of this nation, so do not follow your eyes while performing the prayers.” Al-Saduq has said, “I have heard some mentors saying this treasure is his son al-Muhassan, the one whom Fatima (A.S.) miscarried when she was squeezed between both doors.” He cites evidence from a narration saying that Muhassan will be at the gate of Paradise. He will be told to enter, but he will refuse saying, “No! I shall not enter till both my parents enter first.”
Al-Majlisi, Bihar al-Anwar, Vol. 39, pp. 41-42. Ma`ani al-Akhbar, pp. 205-07