Is it permissible to choose a system of partnership in ownership between spouses when concluding the marriage contract in Tunisia, and is this condition considered invalid and nullifying to the marriage, and what should a young man do if he chooses it?

The condition mentioned regarding the ownership of all earnings between spouses is a void condition because it contains gharar (excessive uncertainty) and involves consuming wealth unlawfully. It differs from a permissible partnership contract. However, the marriage itself is valid due to the invalidity of the condition. If the condition affects the mahr (dowry), the condition is nullified, and the mahr reverts to a mahr al-mithl (a customary dowry) unless they both agree otherwise. If there is a legal issue preventing the change, the spouses must agree to cancel the condition.