Al-Sahlah Mosque in Iraq is one of the ancient Islamic mosques, and there are some narrations from the Ahl al-Bayt that indicate the virtue of performing prayer in it[1]; as it has been narrated from Ja‘far ibn Muhammad al-Sadiq that he said: «بِالْكُوفَةِ مَسْجِدٌ يُقَالُ لَهُ مَسْجِدُ السَّهْلَةِ، لَوْ أَنَّ عَمِّي زَيْدًا أَتَاهُ فَصَلَّى فِيهِ وَاسْتَجَارَ اللَّهَ لَأَجَارَهُ عِشْرِينَ سَنَةً، وفي رواية أخرى: لَأَجَارَهُ سَنَةً»[2]; “‘There is a mosque in Kufa called al-Sahlah Mosque. If my uncle Zayd had come to it and then performed prayer in it and sought refuge with Allah, He would have granted him refuge for twenty years.’ In another narration, he said: ‘He would have granted him refuge for one year.’” As for Jamkaran Mosque in Qom, it is one of the newly built mosques, and there is no special virtue in performing prayer in it. Rather, attributing its construction to the Mahdi based on an unreliable story from an unknown man called Hasan ibn Muthlah al-Jamkarani is tantamount to fabricating lies against him, and fabricating lies against him is considered a great sin. It has been said that the story was mentioned in the book Tarikh Qom by Hasan ibn Muhammad ibn Hasan al-Qomi, quoting from the book Mu’nis al-Hazin Fi Ma‘rifah al-Haqq Wa al-Yaqin by Muhammad ibn Ali ibn Babawayh, as stated by al-Majlisi[3] and al-Nouri[4]. However, no book with this name has been mentioned for Muhammad ibn Ali ibn Babawayh. The book Tarikh Qom by Hasan ibn Muhammad is no longer available either, and what is available is its translation into Persian by Hasan ibn Ali ibn Hasan ibn Abd al-Malik al-Qomi, who passed away in 805 AH. It does not contain that story or any mention of Jamkaran mosque, except for his saying: “It is said that the first mosque built in this region before the Arabs came to it was the mosque of the village of Jamkaran. It was built by a Muslim man called Khattab ibn al-Asadi, who performed prayer in it alone.”[5] It is clear that this has no connection to that story, and one of the indications that the attribution to Muhammad ibn Ali ibn Babawayh is a lie is what has been narrated from Hasan ibn Muthlah, which is his statement at the beginning of the story: “I was sleeping in my house on the night of Tuesday, the seventeenth of the blessed month of Ramadan in the year 393 AH. When half of the night had passed, a group of people came to the door of my house. They woke me up and said: ‘Get up and respond to Imam Mahdi, the owner of the time, for he is calling you’”; because Muhammad ibn Ali ibn Babawayh passed away in the year 381 AH, therefore Hasan ibn Muthlah could not have told him this story!