Are justice and the ability to bear the costs of marriage two conditions for the validity of a polygynous marriage, or is the contract valid with sin incurred in the event of failure to fulfill them?

For polygyny to be permissible, the ability to act justly among wives is a condition. Thus, whoever undertakes it while fearing injustice commits a sin. However, this is not a condition for the validity of the marriage contract itself. The same applies to someone who marries while being poor; their poverty does not affect the validity of the marriage. However, it is not permissible for him to undertake it unless he discloses his situation to the woman, to avoid harming her. Al-Qurtubi explicitly stated that it is not permissible for a man to marry if he knows of his inability to provide for his wife's maintenance (nafaqah), her dowry (sadaq), or her obligatory rights, unless he makes that clear to her.