All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
We did not find a hadeeth indicating that the Prophet, sallallaahu ‘alayhi wa sallam, stipulated in the marriage contract that ‘Ali would not take another wife in the lifetime of his wife Faatimah . However, we found some scholars who mentioned this as a possible answer to the problematic question pertaining to the objection of the Prophet, sallallaahu ‘alayhi wa sallam, to ‘Ali's wish to marry the daughter of Abu Jahl.
Ibn Al-Jawzi wrote, “It is possible that the Messenger of Allaah, sallallaahu ‘alayhi wa sallam, had set the condition when marrying Faatimah to ‘Ali that he would not take another wife with her. Such a condition is valid, and this could be the reason for the objection of the Prophet, sallallaahu ‘alayhi wa sallam, to his second marriage, saying to him, ‘I do not give my consent to it’...” [Kashf Al-Mushkil min Hadeeth As-Saheehayn]
The woman's Wali (legal guardian) or the woman herself has the right to stipulate that the husband does not take another wife with her according to the view of some scholars. Other scholars held that such a condition is not valid. Ibn Qudaamah underlined the difference of opinion among scholars in this regard. The majority of scholars held that such a condition is invalid, whereas the Hanbalis maintained that such a condition is valid and binding on the husband.
Allaah knows best.