Question 075: So in shia duaas and sufi duaas. We here “Abul Qasim” mentioned. Is this referring to the Rasulallah SA or Mehdi A.S? Or referring to it dually?
Answer 075: This kunya is describing the Holy Prophet (pbuh) as father to his son Qasim ibn Muhammad.
Kunya is the name of an adult derived from his or her eldest child and it is expressed by the use of abū or umm. Kunya is a surname.
During the time of the Holy Prophet (pbuh), people call each other by this kind of nickname. They called the Holy Prophet (pbuh) Abul Qasim due to that matter.
The word Kunya is honor to a person. It is specially used for women to not let her name disclosed, like umm for mother and abu for father.
Kunyah sometimes used for belittling somebody, like what Allah named one of the uncles of the Holy Prophet Abi Lahab. Also, the holy Prophet (pbuh) called Amr bin Hisham as Abu Jahl. Or Ali bin Abi Talib called Hajjaj bin Yousif as Abuwazhah (name of Scarab).
Kunya can also be used if you don’t have child, like Abu Hureyra that he didn’t have any child with name of Hureyra. His real name was Abd Shams bin Sakhar before Islam and Abdul Rahman in Islam. Hureyra means kitten and Abu Hureyra had a kitten and he loved it, our prophet (pbuh) usually saw him with kitten and one day our Prophet (pbuh) called him Abu Hureyra means father of kitten.
This is another thing that our Prophet (pbuh) restricted us from using own Kunya. It can be personal reason. The following Hadith gives another restriction,
While the Prophet (pbuh) was in the market, a man called (somebody), “O Abu-l-Qasim!’ The Prophet (pbuh) turned to him and said “Name yourselves after me but do not call yourselves by my Kuniya.”
Abul Hasan and Abul Husain were two Kunyas for Imam Ali (as). However, there has been mentioned some Kunyas (more than 15 titles) for Imam Ali (as), but he would like to be called by Abu Turab (Arabic: أبو تراب) the Father of Soil. Because, this Kunyah was given to Him by the Holy Prophet (pbuh), when he found Ali (as) sleeping while covered with soil, according to narrations.
For further information on this issue, please refer to the following answers:
Index: Titles of the Holy Prophet (pbuh) mentioned in the Holy Quran and Traditions, answer 025.
Index: The daughters of the Holy Prophet (PBUH), answer 291.
 . Amid, Farhang Farsi Amid, Vol. 2, Pg. 1659.
 . Al-Kamil fee al-Lughat wa al-Adab, 1388 A.H, Vol. 2, Pg. 104.
 . Majlesi, Bihar al-Anwar, 1403 A.H, Vol. 18, Pg. 237.
 . Nahjul Balaghah, Pg. 116.
 . Ibn Saad, Vol. 4, Pg. 329; Tirmidi, Vol. 5, Pg. 686; Hakim, Vol. 3, Pg. 506; Ibn Is’haq, Pg. 286.
 . Al-Tabaqat al-Kubra, Vol. 1, Pg. 96; Sahih al-Bukhari 3537 – Book 61, Hadith 46.
 . Amini, al-Ghadir, Vol. 6, Pgs. 337-338.