Back to al-Zubayr’s narration:
• ʿUmar ibn ʿAlī and Ruqayyah the Elder were twins.
Their mother was al-Ṣahbāʾ—some say her name was Umm Ḥabīb bint Rabīʿah of the Banū Taghlib, one of the captives taken by Khālid ibn al-Walīd.

126 – al-Ḥusayn narrated to us; ʿAbd Allāh narrated to us. Al-Zubayr said: my uncle related to me that ʿUmar ibn ʿAlī was the last child of ʿAlī ibn Abī Ṭālib, may Allah honor his face. He travelled to al-Walīd ibn ʿAbd al-Malik as part of a delegation with Abān ibn ʿUthmān, seeking appointment over his father ʿAlī’s charitable endowment, which at that time was being administered by his nephew Ḥasan ibn Ḥasan ibn ʿAlī. Al-Walīd offered him a stipend and to settle his debts, but ʿUmar said, “I have no need of that. I came only for my father’s endowment; I am more entitled to it. Write me its custodianship.”

Al-Walīd therefore wrote him a note that contained lines by al-Rabīʿ ibn Abī al-Ḥuqayq ⦗102⦘, the Jew:

Whenever the pulls of passion sway,
And every ear attends the speaker,
While minds collide in heated strife,
We rule—decisive, just, and fair.
We never take falsehood as truth,
Nor smear the truth with what is false;
We fear our reason being scorned,
And time consigning us to oblivion.

He handed the note to Abān and said, “Give it to him and let him know that I admit none of the children of Fāṭimah, daughter of the Messenger of Allah—peace be upon them both—other than these.” ʿUmar departed in anger and refused to accept the stipend.