ANSWER:

This is permissible. 

It’s the choice of the guy to accept such a condition or not.

Is it permissible for a girl to state a condition that her husband-to-be would not marry another woman in her nikah contract?

Marriage Contract | December 1, 2020 7:52 pm
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Is marriage done on an actual contract where we need to sign or can we avoid this and just do it verbally? Also does it need to be registered with the law of the country?
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I’ve seen people to sign their wedding contracts or do nikah in masjids where the imam and other Muslimeen sit and pray for the newly wed. Is this from the sunnah? If it’s not a sunnah and if there’s nothing mentioned about it in the sunnah, where would you recommend us to sign our wedding contracts or do nikah?