بسم الله الرحمن الرحيم

The primary reason why Prophet Muhammad (saw) did not take Bibi Zainab (sa) for the event of Mubahila cuz Mubahila required the presence of the leaders or representatives of each party I.e Muslims & Christians .

In the incident of Mubahila with the Christians , Prophet Muhammad (saw) took his closest family members who were “recognized leaders” and “symbols of the Muslim community at that time”

• Imam Ali (as)

• Bibi Fatima (as)

• Imam Hassan (as)

• Imam Hussain (as)

These individuals were chosen to represent the strength, unity, and spiritual authority of the Islamic community in a direct challenge against the Christians.

• Allah Subhanahu Wa Ta’ala said:

فَمَنۡ حَآجَّكَ فِيهِ مِنۢ بَعۡدِ مَا جَآءَكَ مِنَ ٱلۡعِلۡمِ فَقُلۡ تَعَالَوۡاْ نَدۡعُ أَبۡنَآءَنَا وَأَبۡنَآءَكُمۡ وَنِسَآءَنَا وَنِسَآءَكُمۡ وَأَنفُسَنَا وَأَنفُسَكُمۡ ثُمَّ نَبۡتَهِلۡ فَنَجۡعَل لَّعۡنَتَ ٱللَّهِ عَلَى ٱلۡكَٰذِبِينَ

• “Then whoever argues with you about it after [this] knowledge has come to you – say, “Come, let us call our sons and your sons, our women and your women, ourselves and yourselves, then supplicate earnestly [together] and invoke the curse of Allah upon the liars [among us].””

(QS. Aal-i-Imraan 3: Verse 61)

Here our sons refer to the two Hassan (as) & Hussain (as) and our women refer to Bibi Fatima (sa) and ourselves refer to Prophet Muhammad & Ali (as).

• Imam Jafar al-Sadiq (AS) said: “When the verse of Mubahila was revealed, the Messenger of Allah (SAWW) called Ali, Fatimah, Hasan, and Husayn. He said, ‘O Allah, these are my Ahlul Bayt.'”

(Reference: Al-Kafi, by Shaykh al-Kulayni, vol. 5, p. 555)

~Jazakallah