What is the ruling of Islamic law on working in a project of renting wedding platforms (kushaf afraḥ) and their accessories, as well as furnishing for weddings and funerals, and is the income from it lawful or unlawful?

The basic ruling for renting wedding supplies is permissibility, and the income from it is lawful, unless the lessor knows that the lessee will use them in a wedding that involves forbidden شرعية matters such as intermingling (اختلاط) and the bride's appearing unveiled. In such a case, it becomes unlawful (حرام) because it constitutes cooperation in sin. As for renting carpets and chairs for mourning gatherings (مآتم), it is permissible but disliked (مكروه), due to people gathering at the deceased's family for condolences. It is advised to work in projects that are free from doubts.