Is it valid in Islamic law for a wife to stipulate in the marriage that her husband may not take another wife, and must the husband comply?

Summary

Scholars differ on this stipulation. The Hanafi, Maliki and Shafi'i schools regard it as invalid, void or disliked, yet the marriage contract remains valid. The Hanbali school treats it as valid and allows the wife to seek annulment if the husband breaches it, with Ibn Taymiyyah favouring the view that compliance is obligatory. In the Hanbali discussion, a condition requiring the husband to divorce his existing wife is not permitted, and the right to annulment lapses if the wife consents to the breach.

Written in our own words from the original fatwa — check the source before acting on it.