whatever a group of learned sunni scholars and some of the shia writers have mentioned about the characteristics of Mahdi's occultation are all lacking authentic reference(s). how good it would have been if they had mentioned those references.
i think the author of 'sawa'eq' has neither emerged from the land of hejaz nor entered the country of iraq nor visited samerra. otherwise, he would have realized that this matter bears no truth. apparently, the source of this rekoning that the shias believe Mahdi to have disappeared in the cellar is this that they see the shia ithna-ashar visiting the holy place of 'sardab' (cellar). it is necessary over here to mention the reason for visiting the holy p-lace of 'sardab' (cellar).
therefore we say: as per the historical books, the holy courtyard which is the mausoleum of ali-ibn-muhammad hadi and hassan-ibn-ali askari and that courtyard which is behind their holy mausoleum and that courtyard in which the cellar is located were all places of residents of those eminent personalities. some of the great islamic scholars like thaqatul-islam nuri have stressed on this matter.
since Mahdi (a.s.) is not having any specified place to be visited, it is better to visit him in his house. on the contrary, it even seems proper to visit his house itself because visiting the friends houses after they have left it is amongst the customs in force. (amongst friends)
in this regard, a poet says: ---
amongst the houses i pass over the house of laila i kiss this wall and that wall. love of the house has not captivated my heart but the love of the one who was residing in it has captivated my heat.
verily this matter has been the reason for the shi'ites visiting the cellar even though this reason is hidden and unknown to many. visiting the 'sardab' (cellar) is a good trend and a cordial custom which has become the motto of the shi'ites and how good and proper this act appears to be even though i have not seen any text or traditions in this regard.
rather, we have not come across any of the books with any supported tradition which commands us to visit hazrat Mahdi (a.s.) especially in the place of 'sardab'.