A believer should always mention Imam (as) with the best of the titles. For example, Hujjat, Qaem, Mahdi, Sahibul Amr and Sahibuz-Zaman etc. He should refrain from uttering his actual name, which is the name of Holy Prophet (sawa): (M – H – M – D).
There are varying opinions among the scholars, as regards the pronouncing of the name of Imam (as). Some have given unrestricted permission, some have prohibited it completely, some have allowed it except in Taqiyya (dissimulation or concealment) and some consider it Makrooh (detestable).
Others maintain that the prohibition of uttering his name was restricted to the period of lesser occultation (Ghaybat Sughra).
In spite of various opinions the following are accepted facts:
Thus, precaution demands that we avoid mentioning the real name of Imam (a.s.) in assemblies and gatherings and refer to him only by his well-known titles. However, we should only use the titles that are mentioned in the traditions so that we do not contravene the rules of Islam. Secondly, the hadith prohibiting mention by name does not include other, not so famous names, i.e. Ahmad etc.
The book Najmus Saqib by Mirza Husain Noori Tabarsi (ra) mentions more than 130 names of Imam Mahdi (as). Some of these are given below:
Traditions inform us that Allah likes that his servants call out to him by different names. Quran itself announces
“And for Allah are the best names. Then invoke Him by them” (Chapter 7 verse 180)
This is relevant for Ahle Bayt (as) as well. They too like it and it is their Sunnat to be known and be called by different titles. Pay attention to the words of Dua Nudba in which Imam Mahdi (as) is called out affectionately by so many titles – O son of the Messenger of Allah, O son of Ali, O son of Fatemah and Khadijah…we too should try and call out to Imam Mahdi (as) by different titles.